Confusing Diabatic and Adiabatic Processes within the Climate Theory:
A Reply to Dr. Roy Spencer’s Blog Article “Giving Credit to Willis Eschenbach”
Ned Nikolov, Ph.D.
Physical Scientist
In a recent blog post, Dr. Roy Spencer at the University of Alabama at Huntsville attempted to criticize and dismiss the importance of our recent discovery about the physical nature of the atmospheric “Greenhouse effect” (Nikolov & Zeller 2017). I normally do not reply to blog articles, but this one reflects a fundamental generic confusion in the current climate theory that is worthwhile addressing for readership clarification. In his blog, Dr. Spencer demonstrated several misconceptions about our work that could be due to either not having read/understood our papers or perhaps an incomplete grasp of thermodynamics. The fact that Dr. Spencer cites a newspaper article about our research instead of the actual published paper may indicate a lack of familiarity with the technical details of our study. These are some key misrepresentations that I spotted in his article:
1. Dr. Spencer incorrectly referred to our main finding as a “theory” when, in fact, it is a discovery based on vetted NASA data extracted from numerous published studies. This empirical pressure-temperature (P-T) function emerged from reported NASA measurements in the process of Dimensional Analysis, which is an objective technique employed in classical physics to derive/extract physically meaningful relationships from observed data.
As discussed in our paper, the new interplanetary P-T relationship shows features of a possible heretofore unbeknown macro-scale physical law given its high accuracy, broad environmental range of validity, and statistical robustness. Hence, this relationship is not a coincidence and demands a theoretical explanation that we provide in the paper by comparing it to other well-known P-T physical relationships. Thus, our study is rather different from the work of Fourier (1827), where he conjecturally proposed what is now known as the atmospheric “Greenhouse” effect. His proposal was later accepted on faith by Arrhenius (1896) and Callendar (1938). These researchers were not able to distinguish between gas IR absorption measured in a laboratory and the surmised “radiant-heat trapping” in an open atmosphere, which has never been observed. The “Greenhouse” concept is an example of a “contrived theory” based on conjectures that requires proof (i.e. empirical verification), while ours is an empirical fact that begs for a theoretical interpretation. Dismissing an observed pattern such as our highly accurate cross-planetary P-T relationship using “theoretical” arguments is backward to the Standard Scientific Method. Yet, Dr. Spencer employed a misconstrued thought experiment suggested by Willis Eschenbach in Jan of 2012 as a tool to “disprove” our empirical findings published in a 2017 paper?! Such an approach only raises eyebrows, as it indicates an inability to distinguish facts from fiction. Furthermore, we have addressed the conceptual and math errors made by Willis Eschenbach in a reply dated Feb 9, 2012, which Dr. Spencer failed to mention in his critique.
2. Dr. Spencer did not consider the role of adiabatic processes in atmospheric dynamics that are complimentary to the well-understood diabatic heating by solar radiation. An adiabatic process alters the internal kinetic energy and temperature of a gaseous system without exchanging heat or matter with the surrounding environment. The change of internal energy in this process is solely due to a change of system’s internal pressure. The adiabatic process emerges from combining two fundamental laws of Thermodynamics: Conservation of Energy and the Ideal Gas Law! Since pressure is a force per unit area, it is intimately related to kinetic energy because, in gases, Kinetic Energy (Joule) = Pressure*Volume. The direct effect of pressure on temperature (i.e. the adiabatic heating & cooling) is evident in all thermodynamic systems. A classic example of a sustained global adiabatic thermal effect in the troposphere is the well-known decrease of temperature with altitude known as adiabatic lapse rate. It is caused by a temperature change (dT) with pressure and the pressure decrease (dP) with altitude (z), i.e. dT/dz = -(dT/dP)(dP/dz). The observed vertical pressure gradient is the core reason for the existence of a negative lapse rate in the troposphere. The magnitude of the actual lapse rate, however, depends on the strength of surface solar heating and other factors such as vertical moisture profiles. Many scientists (Dr. Spencer including) confuse the lapse-rate cause with factors controlling the lapse-rate magnitude. Other common examples of adiabatic heating in the atmosphere include Chinook winds, Santa Ana winds, and Sudden Stratospheric Warming. Air convection and cloud formation could not occur without the adiabatic cooling/heating experienced by rising/falling parcels of air as they move through tropospheric levels of various pressures. In fact, as pointed out in our paper, no thermodynamic system can possess kinetic energy and temperature above absolute zero without some form of pressure present. Even electromagnetic (EM) radiation has pressure! Thus, an EM flux commonly measured in W m-2 is basically a product of photon pressure (in Pascal, Pa) and the speed of light (m/s) when decomposed into its fundamental physical units, i.e. 1 W m-2 = 1 Pa*m/s. Disregarding adiabatic processes in a thermodynamic system such as the atmosphere is equivalent to ignoring (misunderstanding) half of the system’s behavior. Our analysis of NASA planetary data revealed that the Atmospheric Thermal Effect (currently known under the incorrect name “Greenhouse effect”) is a stable form of a macro-scale adiabatic heating caused by a permanent air compression at the surface that is independent of gaseous composition. This is illustrated in Fig. 4 of our paper reproduced below (the ratio Ts/Tna on the vertical axis quantifies the atmospheric thermal effect). This result is in full compliance/agreement with the classic Thermodynamic theory and does not violate any natural laws. Specifically, an adiabatic (pressure-induced) warming cannot violate the First Law of Thermodynamics as claimed by Dr. Spencer, because it is derived from that Law!
3. As well as misunderstanding adiabatic processes, Dr Spencer overlooked a crucial new finding in our study: Atmospheric long-wave radiation is a manifestation (or byproduct) of the kinetic energy in the troposphere, rather than a cause for such energy. This is discussed on p. 14 of our paper:
As with any other gaseous system, the internal energy of the troposphere (measured in Joules), which gives rise to both air temperatures and long-wave radiation, is determined by the product Pressure*Volume. The pressure is set by atmospheric mass, Earth’s surface area and gravity, while the tropospheric volume is controlled by solar heating. The atmospheric volume varies with solar insolation/heating as indicated by the observed difference in tropopause heights between Equator and the Poles, while the surface air pressure is mostly independent of solar radiation and temperature. Dr. Spencer claims that our concept violated the First Law of Thermodynamics (Conservation of Energy), because our model does not consider atmospheric IR back radiation. First, it should be pointed out that an empirical model derived from measured data cannot violate Nature’s laws, because it reflects reality! The fact that our regression model accurately describes the global average surface temperatures of planetary bodies throughout the Solar System without explicitly considering long-wave IR radiative fluxes indicates that such fluxes are not a needed component for predicting global temperatures! That’s consistent with the notion that the IR back radiation is a consequence (result) of atmospheric temperatures. Secondly, viewing the IR back radiation as a separate energy source to the surface that augments the solar flux as done by Dr. Spencer in an effort to explain Earth’s elevated temperature above the Stefan-Boltzmann (S-B) “no-atmosphere” value is physically and methodologically incorrect for the following reason. According to the “Greenhouse” theory, the IR back radiation represents a wavelength-transformed solar flux (from short-waves to long-waves). Yet, it is also interpreted as a diabatic (external) energy source to the surface. This self-contradictory view leads to an inexplicable paradox. The solar radiation absorbed by the entire Earth-atmosphere system is ~240 W m-2. However, the average down-welling IR radiation in the lower troposphere is measured at 342 W m-2 while the IR flux emanating from the surface is ~398 W m-2 (see the 2013 IPCC AR5 energy-budget diagram).
If the Sun were the sole source of energy to the climate system as claimed by the “Greenhouse” theory, how could long-wave IR fluxes in the lower troposphere exceed the total absorbed solar flux by more than 40%? The discrepancy between short- and long-wave radiative fluxes becomes extreme on Venus: that planet only absorbs 65 W m-2 solar radiation due to a 90% cloud albedo, while its lower troposphere emits >15,200 W m-2 IR flux towards the surface! This paradox cannot be explained by a simple absorption and re-emission of solar radiation, because such a mechanism cannot elevate (especially in the presence of convection) the tropospheric internal kinetic energy above the net solar input as observed in reality. It’s also important to note that the re-radiation of IR energy is qualitatively different from and should not to be confused with reflection. Greenhouse gases do not reflect IR radiation! Therefore, trying to explain the down-welling IR flux and surface temperature diabatically, i.e. through radiative fluxes alone, leads to a conflict with the First Law of Thermodynamics, since such an explanation effectively creates energy out of thin air. Thus, it must be physically incorrect. Our discovery of the adiabatic nature of the Atmospheric Thermal Effect provides a new feasible way to explain the observed energy-flux paradox without violating Nature’s laws. Air pressure caused by gravity acting on the atmospheric mass enhances (by virtue of its force) the amount of solar energy absorbed directly or indirectly by the atmosphere. This adiabatic thermal enhancement is consistent with the First Law of Thermodynamics and evident in the general form of the semi-empirical Equation for calculating the average surface temperatures of rocky planets (Ts) derived in our paper, i.e.
Ts = Tna Ea
where Tna is the planet’s surface temperature in the absence of atmosphere (i.e. the S-B temperature value), and Ea is the adiabatic atmospheric thermal enhancement quantifying the relative effect of pressure on temperature. For planetary bodies with no atmosphere, Ea = 1.0. For bodies with an atmosphere, Ea increases above 1.0 as a non-linear function of total pressure reaching 3.18 for Venus (the rocky planet with the most massive atmosphere in our Solar System). For Earth Ea = 1.459 , which means that our atmosphere boosts Planet’s average surface temperature 45.9% above its S-B value.
4. Finally, Dr. Spencer confuses one’s ability to observe/measure IR back radiation with the correctness of one’s understanding about the role of that radiation in global climate and the Atmospheric Thermal Effect. No one denies the existence of long-wave radiative transfer and IR back radiation in the atmosphere, but its global meaning has been misinterpreted for nearly two centuries. Just as it was “obvious” to medieval scholars studying the movement of heavenly bodies that Earth was at the Center of the Universe, since all lit objects in the sky seem to revolve round us, so too it has been “obvious” to climate scientists for 190 years that the down-welling IR radiation was responsible for the warming effect of Earth’s atmosphere. It took a proper placing of Earth in the context of a cosmic continuum of climate drivers to discover that the IR back radiation was in fact a byproduct (an effect) of Sun’s diabatic heating and atmosphere’s adiabatic enhancement of the amount of absorbed solar energy.
In conclusion, the “radiative Greenhouse effect” does not exist. The atmosphere warms the surface thermodynamically through a form of adiabatic compression that only depends on total pressure. Adiabatic processes, although well understood in classical Thermodynamics, are not part of the current climate theory, which focuses almost exclusively on diabatic radiative processes. As a result of this conceptual bias, climate-science classes taught at Universities do not properly explain the direct effect of pressure as a force on the temperature of thermodynamic systems. Instead, pressure is only discussed as a factor affecting the atmospheric IR optical depth assumed to control surface temperature through a purported “trapping” of radiant heat, which is not observed in the open, convective atmosphere.
The above points are clearly explained in our 2017 paper. It is therefore puzzling why Dr. Spencer failed to grasp them assuming he had read the paper. Or maybe he hasn’t? The thought experiment proposed by Willis Eschenbach in 2012 (i.e. 5 years prior to the publication of our paper!) to “disprove” our findings has no basis in real physics and reflects a poor understanding of thermodynamics. While such a dismissive and indefensible position might be excusable for Mr. Eschenbach, who has no formal education in physical sciences, it is certainly inexcusable for Dr. Spencer to claim that our empirical results backed by vetted NASA data and fully explainable by adiabatic processes represent a “violation of the fundamental 1st Law of Thermodynamics: Conservation of Energy”.
My big question regarding the above debate is this: Why do some “climate skeptics” such as Dr. Roy Spencer, Anthony Watts and Wills Eschenbach go out of their way to defend a discombobulated 19th-Century theory, which is at the heart of the anthropogenic climate-change exaggerations that they claim to have been fighting against for decades? It makes no rational sense for skeptics to argue ad nauseam about marginal issues such as rates of warming or sea-level rise while vigorously protecting by all means the rotten core of a concept that allows the promotion of exaggerated claims about such issues to be made in the first place.
Tallbloke's Talkshop 
oldbrew says: January 28, 2019 at 1:44 pm
Better think of the atmosphere as expanding against gravity.
The internal gas pressure pushes the air up against gravity.
Increase surface temp. => atmosphere expands
Decrease surface temp => atmosphere shrinks
Complicating factor is the compressability of air.
Difference in surface temperatures create different pressures at equal altitudes higher up, creating Hadley circulation, jet streams etc.
oldbrew says: January 28, 2019 at 9:33 am
Being close makes a difference.
oldbrew says:
January 28, 2019 at 9:33 am
Another conundrum?
The Moon has an exceptionally low albedo, giving it a reflectance that is slightly brighter than that of worn asphalt. Despite this, it is the brightest object in the sky after the Sun.
https://en.wikipedia.org/wiki/Moon#Appearance_from_Earth
Still bright in Earth’s daytime.
gallopingcamel says: January 28, 2019 at 4:57 am
Seeing the pressures at Venus I assume at some level the CO2 becomes liquid. Isn’t the difference between gaseous and liquid CO2 (part of) the explanation?
So the rocky surface is actually an ocean floor and somewhere higher up we see an ocean surface.
gbaikie says: January 27, 2019 at 12:45 pm
Ãn ideal BB at our distance from the sun in RADIATIVE balance would have an average surface temp. of ~165K.
Your calculation is for ENERGY balance.
See this comment and 2 more further down.
https://www.sciencetalks.nl/heating-the-natural-greenhouse/#comment-49
My point is that the entire oceans have been heated by geothermal, starting at their creation when Earths surface was magma all over.
Since that time their temperature has been maintained by geothermal energy.
Lucy Skywalker says: January 27, 2019 at 5:45 pm
What you describe is usually called the Environmental Lapse Rate (ELR), average ~6,5K/km for mid latitudes.
This is NOT the adiabatic lapse rate.
The image above this text DOES show the Dry Adiabatic Lapse Rate:
rising or sinking air warming/cooling at 9,8K/km.
Explanation is given in beginners courses Meteorology.
Suggest to get at least the basics correct before going of in all kind of wild theories.
“rising or sinking air warming/cooling at 9,8K/km.”
should be
“rising or sinking air cooling / warming at 9,8K/km”
Mike Flynn: If you believe that all gases have the same density, creating the same mass per unit volume, this is indeed new science.
You’re introducing unnecessary complication. We don’t need to consider mass per unit volume to calculate average surface pressure. We just need the gravitational constant, the surface area of the sphere, and the entire mass of the atmosphere.
Maybe you prefer the MetOffice –“In turn the atmospheric pressure depends on the weight of the air under gravity. The weight of a given thickness of atmosphere depends on its temperature, because warm air is less dense than cold air.” And gaseous H2O is less dense than dry air – about 0.62 compared to 1.0. CO2 about 1.62. So, denser – more pressure. Less dense – less pressure. All other things being equal. Composition makes a difference, it seems.
Once again, you’re introducing unnecessary complication. The MET office is explaining pressure variation within the atmosphere. Ned and Karl are talking about the longterm average baseline pressure of the entire atmosphere, not the weather and minor local pressure variation occurring within it.
You are trying to avoid the N&Z claim that pressure creates heat.
N&Z don’t claim that “pressure creates heat”, that’s just either your disingenuity or misunderstanding.
If you believe they do make that claim. Quote the relevant part of their paper to back up your assertion. That’s the way we do it on the talkshop.
Trick: Atmospheric mass has to be a function of composition so surface pressure IS a function of atm. composition.
Atmospheric mass is the total mass of all gaseous constituents of the atmosphere, no matter what those are. Therefore the surface pressure will be the same whether the composition is 80%N2 and 20%O2 or the opposite, providing that the total mass is the same.
And 10:48am: ”have you read the extensive discussion of Mars’ surface T in appendix B of Ned and Karl’s second paper?”
If you do read App. B, find N&Z…
You should, rather than relying on Trick’s partial rendition of it.
Ben Wouters says: Being close makes a difference.
Does shining a bright light on ‘worn asphalt’ e.g. a road surface, from (let’s say) 1 metre away, make it as bright as the Moon which is ~400,000 km. away from Earth?
tb writes 4:44pm:”Therefore the surface pressure will be the same whether the composition is 80%N2 and 20%O2 or the opposite, providing that the total mass is the same.”
Of course tb, your premise is your conclusion. If each N2/O2 molecule in an atm. were replaced with H2 molecule though, the atm. would be less mass, less total surface pressure, & on earth lost to space as most of the primordial H2 is now gone having reached escape velocity at terrestrial temperatures over eons. Atm. composition does matter for surface pressure. That composition can change over time affecting planetary mean surface P & T.
”N&Z don’t claim that “pressure creates heat”, that’s just either your disingenuity or misunderstanding.”
N&Z do claim their planetary PTE is due to compressional heating. I also recommend reading N&Z paper, do not rely on any clip, read the full context before commenting to find: “Adding a force such as gas pressure to a physical system inevitably boosts the internal kinetic energy and raises its temperature, a process known in thermodynamics as compression heating. The direct effect of pressure on a system’s temperature is thermodynamically described by adiabatic processes. The pressure-induced thermal enhancement at a planetary level portrayed in Figure 4 and accurately quantified by Eq. (10a or 11) is analogous to a compression heating, but not fully identical to an adiabatic process.”
Trick: N&Z do claim their planetary PTE is due to compressional heating. I also recommend reading N&Z paper, do not rely on any clip, read the full context before commenting to find: “Adding a force such as gas pressure to a physical system inevitably boosts the internal kinetic energy and raises its temperature, a process known in thermodynamics as compression heating. The direct effect of pressure on a system’s temperature is thermodynamically described by adiabatic processes. The pressure-induced thermal enhancement at a planetary level portrayed in Figure 4 and accurately quantified by Eq. (10a or 11) is analogous to a compression heating, but not fully identical to an adiabatic process.”
I’m not seeing the phrase ‘creates heat’ anywhere there. Let’s wait and see what Mike Flynn comes back with.
Fair enough tb, those were Mike Flynn’s words which I didn’t quote, I would also encourage Mike Flynn to quote from the paper instead of a useless strawman of the commenter’s own words.
re: Mike Flynn says: January 28, 2019 at 11:43 am
Average atmospheric pressure at a point on the surface depends on gravitational strength and the total mass (weight) of the air above it, regardless of composition. i.e., a ton of CO2 doesn’t weigh more than a ton of gaseous H20. I’m not sure what Tallbloke meant by surface area being a factor; I don’t think it is.
Hi Dan. Pressure is defined as a force per unit area. 0.000145 pounds per square inch for example is one Pascal, equal to one Newton per square metre. So we need to know the area the action of gravity on the total atmospheric mass is being applied to.
Mike Flynn says: January 28, 2019 at 2:33 am
Facts are facts – regardless of what you or I might think. As Feynman wrote – “It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are. If it doesn’t agree with experiment, it’s wrong.” I’ll go a little further – if your experiment cannot be reproduced, it doesn’t count.
LS: I totally agree with every word of yours here, I am saying the same!
Graeff’s experiments however CAN be reproduced – in fact, he did over 500 variants of what is essentially the same experiment – and I joined his seminar precisely to see the evidence of this, and to voice the toughest doubts I could muster as to repeatability. I’m really glad I understood it well enough and wrote it up carefully enough here for it to be possible, from my descriptions, for the experiments to be taken up again by others, should they want to – because THEY SHOULD BE. If as I suspect they haven’t been taken up by anyone else so far – it does NOT mean they cannot be taken up. Of course they can. Even if only to report failure. Replication would be such a cinch to any reasonably equipped lab. Graeff used cheap waste sources. I had hoped to do it myself.
IIRC, Graeff invited several universities to replicate but all refused, or prevaricated, or said yes then nothing happened. Why? Was this because there was a fatal flaw in the experiments? I don’t think so! I think it was because they are so well designed that, reproducing them, one cannot avoid facing the challenge they pose to the conventional statement of the Second Law of Thermodynamics. But this is only the superficial appearance, and misses the key point which emerges when one really grasps Graeff’s brilliant and simple theory, which is that they not only support the Second Law, they amplify it. AND they give the missing experimental and theoretical backup, at the molecular level, for why N&Z are right to replace the GHG hypothesis with their adiabatic thesis. Graeff supplies what Monckton rightly, IMHO, asks N&Z for. Monckton won’t believe N&Z without more than simple curve-fitting to the planetary data: he wants theory and reproducible experiment that backs up their finds. I’ve explained all Graeff’s stuff in my articles, url’s at https://tallbloke.wordpress.com/2019/01/17/nikolov-zeller-reply-to-dr-roy-spencers-blog-article/comment-page-1/#comment-146215 . Have you read them? Study the first three!
MF: Graeff’s patent application claimed inexhaustible free energy. As far as I am concerned, such claims are rubbish, bollocks, nonsense, delusional . . ., until demonstrated otherwise by means of reproducible experiment – based on my experience and knowledge.
LS: again I agree totally. We do, however, have demonstration of this energy in such phenomena as the Föhn and Chinook winds – the problem there is it is not a “reproducible experiment” and cannot easily be harvested. However, as I said elsewhere, Iceland harvesting geothermal energy IS cost-efficient. Most people believed that flying was impossible until it happened – and the same is true of all paradigm-shifting engineering. Si monumentam requiris, circumspice.
Re – tallbloke says: January 28, 2019 at 10:10 pm
According to modern estimates, the surface area of the Earth is approximately 510 million square km (5.1 x 108 km2) or 196,900,000 square miles.
https://www.universetoday.com/25756/surface-area-of-the-earth/
Just add on a bit more to get the surface area of the atmosphere?
Tallbloke,
From N&Z –
“The ‘greenhouse effect’ is not a radiative phenomenon driven by the atmospheric infrared optical depth as presently believed, but a pressure-induced thermal enhancement analogous to adiabatic heating and independent of atmospheric composition;”
“The relative atmospheric thermal enhancement (T s /T na ratio) as a function of the average surface air pressure”
“In the case of an isobaric process, where pressure is constant and independent of temperature such as the one operating at the Earth surface, it is the physical force of atmospheric pressure that can only fully explain the observed near-surface thermal enhancement (NTE).”
If you want to state clearly and unambiguously that atmospheric pressure (due to gravity) does not create heat, I would appreciate it. That would clear the matter up.
N&Z seem to be claiming something. You seem to be annoyed with me for using a particular phrase “creates heat”. I would be happy if you tell me where N&Z specifically state that atmospheric pressure does not “create heat”.
I note you have added PTE to the list of acronyms which avoid claiming that atmospheric pressure makes thermometers hotter, without creating heat.
You haven’t got a useful definition of any of these non-heat creating thermometer heating processs, nor any testable hypothesis for the ATE, the NTE, or the PTE. That’s because the whole idea is without basis, even according to you. You agree that pressure does not create heat, but you lambaste me for actually saying it. Are you trying to say that “thermal enhancement” really means either cooling or no change at all?
The phrase implies heating to me, but maybe N&Z really mean something else. I cannot read their minds.
If atmospheric pressure does not “create heat”, why all the fuss? This is not new science, or a new paradigm – it has been known for quite some time. Likewise, the fact that atmospheric pressure is dependent on gravity, is also well known.
Have I got it right? Neither pressure nor gravity create heat, but pressure makes thermometers hotter, unless I agree, in which case “thermal enhancement” does not mean increased temperatures.
Rubbish. No gravitothermal effect – regardless of pseudoscientific pseudonyms you create to avoid saying gravitothermal.
Cheers.
Re: tallbloke says: January 28, 2019 at 10:10 pm
We’re probably talking past each other here. What I mean is that a column of air will have a given pressure at the bottom, regardless of its cross-sectional area. The unit of measurement is, of course, a reference to some standard such as square inch or square meter. I’m sure we both know what the other means.
Mike Flynn: “I would be happy if you tell me where N&Z specifically state that atmospheric pressure does not “create heat”.”
N&Z don’t specifically state that atmospheric pressure does not create sugar sprinkled lemon pancakes either. It’s very remiss of them.
I always am engrossed by this topic, but I’m not a physicist and wonder if there is a way to make “compression heating” approachable to a layman. N & Z claim it is explained by the ideal gas laws and I think I (sort of) understand, but I never see any comments reflecting my thinking. So I’ll throw this out there hoping not to embarrass myself too much.
The most common formulation of the ideal gas law that I see is: PV = nRT, where
P = absolute pressure
V = volume
n = amount of gas in moles
R = a constant (Avagadro constant)
T = absolute temperature
So, algebraically, T=PV/nR
If you were to look at a square inch (or any unit) of the surface of a planet, the pressure is the weight of all of the atmosphere above it, even if it is so cold as to be liquid. Therefore, P is a constant.
If you were to choose some arbitrary volume of air right at the surface of that planet to observe, V also becomes a constant.
So, the only variable that concerns us is n, which is easy to visualize as some number of molecules of the atmosphere you are observing within V. The relationship ends up being ΔT = 1/Δn. So as n gets smaller, T gets larger.
To make things even simpler, we can even assume a pure N2 atmosphere that cannot absorb radiation and can only be heated by conduction. Therefore, as the surface of our planet heats from incoming solar radiation, some heat is transferred to the nitrogen atmosphere, causing it to expand. In the arbitrary volume (V) we are observing, there are now fewer molecules of N2 (n), meaning that T is necessarily higher.
That’s the nutshell version. I could go on, but the logical progression is fairly obvious.
My question is: am I on the right track? It makes sense to me intuitively, but that doesn’t necessarily mean I’m on to something.
Thanks,
Dan
Dan, total atmospheric mass divided by total area of Earth’s surface turns out to be 1014KPa. That’s all we need to know. But we need to know the area to know it.
Dan asks good questions: ”am I on the right track?”
Couple meteorological points: If you pick a constant volume, say the inside of a Stevenson Screen, the atm. n, P, T and humidity would constantly change according to the gas laws as the constant volume of air is changed.
A more convenient formulation is P=n/V*R*T which is P=density*R*T. Inspection of weather station records show none of these to be constant as the day/night progresses. But of course, your volume would be constant by your def. So that V=constant alone doesn’t mean anything.
”fewer molecules of N2 (n), meaning that T is necessarily higher.”
P=density*R*T shows you if n is less at constant volume, you can only say something about T at constant pressure in the Stevenson Screen which is not observed in records. Weather stations show T can increase while P is increasing OR decreasing because density is not constant. T goes as P only when density IS constant in your volume.
”we can even assume a pure N2 atmosphere that cannot absorb radiation”
N2 gas absorbs radiation across the spectrum feebly, planetary atm. composition does matter for mid-stratosphere measured T, density, P and below. To assume any atm. doesn’t radiate creates a singularity after which you can write/claim anything you want as no one can experimentally prove you wrong…..or right.
Mike Flynn asks 11:05pm: ”Have I got it right?”
No.
However, perhaps Mike could inform blog readers with Mike’s own science reasoning as to why Ts/Tna is observed to increase with total surface atm. pressure as shown in N&Z 2017 Fig. 4 solar system objects (Fig. 1 in top post). Quotes from the paper would be required to adequately determine any difference with N&Z paper that Mike may want to constructively point out.
tallbloke,
Nope. Mass is irrelevant, in the absence of gravity (in this case). Maybe you mean weight, rather than mass?
Atmospheric pressure varies, as the weight of the atmosphere above your sampling point varies.
A cubic meter of, say, CO2, weighs more than a cubic meter of H2O vapour – more than twice as much, in fact. The mass of each will differ.
In any case, neither gravity nor pressure create ATE, NTE, or PTE.
A cylinder of air at 2500 psi. will cool down until the air inside becomes solid, if allowed to do so, all the way to absolute zero, theoretically. So will an empty cylinder (15 psi approx).
So much for pressure causing heating.
So, do N&Z claim that pressure creates heat, or not? What do you say? Any new science, or just speculation unsupported by even a testable hypothesis?
As to “N&Z don’t specifically state that atmospheric pressure does not create sugar sprinkled lemon pancakes either. It’s very remiss of them.”, you are just being silly. I assume you are trying to be gratuitously offensive, or something.
Still no gravitothermal effect resulting in hotter thermometers, is there?
Cheers.
Trick,
“However, perhaps Mike could inform blog readers with Mike’s own science reasoning as to why Ts/Tna is observed to increase with total surface atm. pressure as shown in N&Z 2017 Fig. 4 solar system objects (Fig. 1 in top post).”
Why should I?
Can’t you work it out for yourself? You might be confusing correlation with causation.
Nothing to do with the supposed increased temperatures resulting from gravity causing atmospheres to exert pressure on the planet they surround.
If you believe N&Z have discovered some previously undocumented effect, and have devised a testable hypothesis to explain this effect, good for you. Obviously, observing that gravity creates atmospheric pressure is no great leap forward.
Cheers.
N&Z say without an atmosphere Earth would be 90K cooler. And greenhouse effect theory says without greenhouse gases, Earth with it’s remaining non greenhouse gases as the atmosphere, would be 33 K cooler.
Earth is a planet largely covered with an ocean and you don’t you ocean without there being an atmosphere. Water turns into water vapor in a vacuum and it turns into water vapor if have any kind of atmosphere, H2O ice evaporates at -150 C.
So in a sense, both N&Z and greenhouse effect theory are saying Earth without water. And even the Moon has water. And Moon would have more water if it was not 1/80th of Earth’s
mass.
If Earth is suppose be like the Moon but more massive and lacking water, do we still have Earth like Earth?
Most of Earth is water and ocean floor is young – less than 200 million years old. Or 70% of Earth surface is relatively young (Continental land masses being older). And it thought that Venus surface, is also young.
Or our moon lacks volcanic activity and has no plate tectonic activity. And the Moon surface is mostly billions of years old. And it’s surface has churned with eons of impactors. Pounded into dust, and with the dust pounded into rock. And BTW, it’s regolith has gases embedded in it- hydrogen and helium mostly.
In some ways it seems easier, to imagine Venus without an atmosphere, though we know little of the Venus surface.
I think Venus has less water than Mars, and seems possible, less than our Moon (and possibly, less than Mercury). And it is a bit of mystery, as our solar system has a lot water in it.
@Oldbrew,
“gc – what effect are the clouds having at night?”
Day or night the cloud tops on Venus define the effective temperature of the planet when it comes to outgoing IR radiation.
On Earth the situation is more complex as the cloud cover is not 100%. I have been trying to address this issue using Finite Element Analysis without much success.
on gravity..
“ignoring the effects of air resistance.the speed of a falling object falling freely will increase by about 9.8 metres per second every second.”
on the dry adiabatic lapse rate..
“When the air contains little water, this lapse rate is known as the dry adiabatic lapse rate: the rate of temperature decrease is 9.8 °C/km (5.38 °F per 1,000 ft) (3.0 °C/1,000 ft). The reverse occurs for a sinking parcel of air.”
on the link between the adiabatic dry lapse rate and gravitational acceleration..
“Adiabatic lapse rates are usually differentiated as dry or moist. The dry adiabatic lapse rate for air depends only on the specific heat capacity of air at constant pressure and the acceleration due to gravity. … The greater the amount of vapour, the smaller the adiabatic lapse rate.”
Lucy Skywalker on January 28, 2019 at 10:40 pm
The Föhn effect is another well understood phenomenon. Air is forced up a mountain, clouds form, so the air cools at the MALR while rising “harvesting” latent heat.
ONLY if this moisture rains out the air will warm at the DALR on the downhill part and the air will be warmer at the same altitude as where it started its traject. No mystery here.
Ben Wouters, January 29, 2019 at 8:15 am
. . . No mystery here.
Agreed. And N&Z, and Graeff too, are dealing with other instances of the same phenomenon – the link between pressure, temperature and altitude.
gc – re Day or night the cloud tops on Venus define the effective temperature of the planet when it comes to outgoing IR radiation.
Some clouds reduce heat loss at night.
The Big Question
https://www.nsf.gov/news/special_reports/clouds/question.jsp
Mike Flynn: As to “N&Z don’t specifically state that atmospheric pressure does not create sugar sprinkled lemon pancakes either. It’s very remiss of them.”, you are just being silly. I assume you are trying to be gratuitously offensive, or something.
I was simply illustrating the stupidity of your original proposition.
A cylinder of air at 2500 psi. will cool down until the air inside becomes solid
But this doesn’t seem to have deterred you from making stupid observations that have nothing to do with planetary atmospheres.
So, do N&Z claim that pressure creates heat, or not? What do you say? Any new science, or just speculation unsupported by even a testable hypothesis?
If you were to read their paper instead of speculating about what it contains, you’d discover that what they have done is take empirical data and through the use of dimensional analysis, empirically derived a pressure-temperature relationship. Using this, they have made predictions for the surface temperatures of bodies NASA has yet to obtain accurate empirical data for. We await the results from the planned probes with interest.
Atmospheric pressure varies, as the weight of the atmosphere above your sampling point varies.
It doesn’t seem to make any difference how many times I explain to you that N&Z are discussing long term planetary scale averages of total surface pressure, you keep obfuscating the issue with minor internal variations. Enough, you’re gone.
Trick: To assume any atm. doesn’t radiate creates a singularity after which you can write/claim anything you want as no one can experimentally prove you wrong…..or right.
Everything radiates according to its temperature. Physics 101. The big mistake climate science has made is to assume the thing they measure (radiation) is the cause of the temperature, rather than its effect.
Pressure affects surface temperature in several ways on Earth. The two most important are the way increasing the pressure will suppress the evaporation rate from the ocean surface, and the effect on the rate of conduction from surface to air due to the adiabatic compression heating of descending air parcels.
I tried to summarise these two in a modified NASA energy budget diagram.
Click to access 2060.pdf
This experiment found that 25ml in a 250ml beaker of water at 20C evaporated in ~150 minutes when air pressure was reduced to ~2.86 Torr (381.2952Pa). This is ~266 times lower than Earth’s surface air pressure.
I don’t have a 250ml beaker to hand or the controlled conditions to maintain it at 20C, but I think we all know that it would take days rather than 2.5 hours for the water to evaporate at sea level pressure in the same fairly still conditions (say, out of a cup in our home with central heating running at 20C).
Water evaporating takes quite a lot of heat away — 540 calories per gram — when it evaporates.
https://van.physics.illinois.edu/qa/listing.php?id=1440&t=water-evaporation-rate
So, I think we can conclude that air pressure suppresses the rate of evaporation, and that this means the ocean surface has to rise to a higher temperature in order to lose heat as fast as it gains it from the Sun.
This is one of the ways pressure increases Earth’s surface temperature. Not by “pressure creating heat”, but by reducing the rate at which heat is lost from surface to atmosphere, thus forcing the surface temperature to rise until it can evaporate water fast enough be in equilibrium with the overlying atmosphere.
”The two most important are the way increasing the pressure will suppress the evaporation rate…”
Evaporation depends on the state of the liquid not the state of the gas above the liquid.
Global mean atm. sea level pressure is very close to constant over multi-annual periods observed, there is no meaningful change in suppression in the cartoon’s period studied as the global state of the surface liquid remains ~unchanged i.e. ~steady state equilibrium.
”This experiment found that 25ml in a 250ml beaker of water at 20C evaporated in ~150 minutes when air pressure was reduced to ~2.86 Torr”
What happened to the state of the test beaker liquid during this change in pressure? Fig. C shows the liquid state changed hugely, rapidly thus so did evaporation. This is not what happens to earth global evaporation due to global sea surface temperature changes over multi-annual periods shown in your cartoon; their liquid state changes verrrrry slowly globally in the period studied. Thus, so does global evaporation which depends on that liquid state.
Locally & in short periods (daily, weekly, monthly), yes, you can get weather changes in the water cycle (storms, thunderheads, droughts) but this state change must average out globally & over long periods as observations show very little change in water cycle over global multi-annual periods studied in your cartoon. Climate is the interest here not weather.
For a good discussion of water cycle changes & impacts in the period of the cartoon, I suggest L’Ecuyer 2015 “new energy budget estimates that simultaneously satisfy all energy and water cycle balance constraints.”
https://journals.ametsoc.org/doi/10.1175/JCLI-D-14-00556.1
https://water.usgs.gov/edu/watercycleatmosphere.html
Taking this a little further, this page estimates that If all of the water in the atmosphere rained down at once, it would only cover the globe to a depth of 2.5 centimeters, about 1 inch.
On a square metre, this would be 25000g of water, which would have removed 13.5million calories of heat from the surface as it evaporated, equivalent to 15,700 Watts at a rate of 859.85 calories per hour. The water cycle is around 9 days or 216 hours so dividing 15,700 by 216 we arrive at a figure of 72.68W/m^2
On their energy budget diagram, NASA tells us the rate of latent heat leaving the surface amounts to around 80-90W/m^2, so we’re not too far off with this calc.
So we need to know how long that 25ml of water in a 250ml beaker would take to evaporate at 20C under 1 bar of pressure in order to calculate the rate at which the surface would be losing energy if the air pressure was 266 times lower. And then work out how much colder it would be once equilibrium was restored..
The red arrows shown labeled “compression heating” in your cartoon are not observed in nature. For natural convection, the unevenly heated surface causing rising fluid in a gravity field is actually replaced from horizontal inflows of similar temperature surface fluid. The rising fluid spreads out horizontally when it equilibrates to ambient, that formerly rising fluid largely stays aloft consistent with a mostly hydrostatic atm. Just enter “convection” into youtube and observe the experiments.
“if the air pressure was 266 times lower.”
That would cause a change in state of the liquid since in contact thus, yes, cause a change in evaporation as the test shows.
Actually Trick, air has to descend from on high to restore equilibrium to the pressure gradient. It falls (and adiabatically heats up) particularly strongly at the boundary of the Hadley and Ferrel cells. Google ‘Horse Latitudes’. They’re called that because the adiabatically heated descending dry air dehydrated the horses on the galleons of the Spanish Conquistadores. A typical Spanish Conquistadore solution was found to this problem. They threw the horses overboard.
Also, Trick, see what the MET office has to say about the adiabatic heating of air as it descends during a polar ‘sudden stratospheric warming’ event. Pay special attention to the segment from 52 seconds to 1:11.
The gravitar for Mike Flynn says “No such user”. I detect the personna of Eschenbach in Flynn’s arrogance…….. Such continued “silliness” re N and Z has similarities to early thc use mind bending such as would posit a steel greenhouse, or meaningless equations. Imagining they can overturn a Physics-based Hypothesis. Silliness indeed…… Brett
Willis’ ‘steel greenhouse’ is actually theoretically correct. The problem arises because he then seamlessly slips into applying it to the Earth’s real atmosphere, whilst conveniently forgetting that the steel greenhouse requires a vacuum between shell and surface.
He made a similar error with his ‘Moon is a cold mistress’ article, which I deconstructed here:
Relative humidity, air temperature, wind speed, and solar irradiation control the equilibrium temperature of bodies of water on the surface. Perry and Chilton, 5th edition.
Pochas: Do Perry and Chilton also tell us what controls the air temperature? 😉
I’ll leave that to you.
”Actually Trick, air has to descend from on high to restore equilibrium to the pressure gradient.”
This is not what is observed in natural convection tb.
Hi and lo pressure systems rotate, the low pressure at the bottom created by rising, convecting surface air is replaced by ambient temperature laterally moving air at the surface not air from above. Watch a convection test video. Winds always come from N,E,W,S not always from columns of +z,-z winds. When rising air equilibration occurs, convection stops in upper atm. regions, the air spreads out laterally at ambient in a hydrostatic atm. which happens all along the natural gradient at all levels in the troposphere. Although there is an enormous amount of PE very little PE is available to convert to KE (see CAPE).
The hi and lo pressure systems rotate with horizontal winds (these are called geostrophic) not vertical winds. Any hi pressure compression heating is exactly offset by low pressure expansion cooling (which is where the term adiabatic comes from). This is evidenced by 240in & 240out ~balance steady state equilibrium observed. If there were compression heating by a contracting atm. then the balance might be 240 in and say 250out in steady state equilibrium (1.04 out/in) until the contraction stopped for example but that sort of imbalance is not observed for modern era earth.
Total earth atm. is not observed contracting.
Some of the gas giant atm.s are observed still contracting and contribute to a steady state equilibrium imbalance with more out than in, for example in a certain period observed:
Earth out/in ratio 1.0003
Jupiter out/in ratio 1.67
Saturn out/in ratio 1.84
Neptune out/in 2.64
https://pds-atmospheres.nmsu.edu/education_and_outreach/encyclopedia/heat_balance.htm
”polar ‘sudden stratospheric warming’ event.”
Regional weather event, offset in other regional weather events as observed over multi-annual periods or 240in would be much less than the amount out multi-annually which is not observed for earth.
Trick: convecting surface air is replaced by ambient temperature laterally moving air at the surface not air from above.
Really? What’ll happen when the lateral air has been used up and there’s none left to fill the void left by air convecting to high altitude? Can’t be replaced by descending air according to you.
OMG, we’re all gonna asphyxiate!
Trick: Any hi pressure compression heating is exactly offset by low pressure expansion cooling (which is where the term adiabatic comes from).
You’ve completely missed the point here. I’m not proposing heat is added to the surface by the compression heating of the descending air you don’t believe descends (except now apparently you do), in the same amount as heat is removed from the surface by upwards convection. Or even at all.
Let me quote myself and see if you get it second time around.
“Pressure affects surface temperature in several ways on Earth. [One is] the effect on the rate of conduction from surface to air due to the adiabatic compression heating of descending air parcels.”
Maybe this was too brief for your understanding? The point is: The Earth is heated by the Sun, not adiabatically warmed descending air. What that warmed air does is impede the rate that conduction of surface heat to air takes place at by reducing the temperature differential between them. That forces the surface to rise in temperature to overcome that impedance.
If there were compression heating by a contracting atm…
There isn’t. Stop introducing red herrings right now.
tallbloke says, January 28, 2019 at 10:48 am:
Indeed I have. And I see that their Martian T_s estimate is based on a distinct assumption that turns out to be fundamentally flawed.
They assume (based on a book by a Nadine Barlow (2008)) that the lapse rate on Mars is somehow a universal -4.3 K/km. This is, however, far from the truth. What Barlow actually writes (p.183) is the following:
Click to access barlow.pdf
“Daytime heating results in convection which can lift dust off the surface through dust devil activity from late spring through early summer (Hinson et al., 1999). Convection can extend through an entire scale height (~10km). The temperature gradient in the convective region approaches that of the dry adiabatic lapse rate of ~4.3 K km-1. At night, convection ceases and strong temperature inversions develop. Nighttime temperatures can drop low enough to cause condensation of atmospheric water vapor, producing the hazes and fog commonly seen in the early morning hours. Thermal tides dominate the circulation at altitudes above ~75km, particularly in the tropics, while planetary waves dominate at lower altitudes (Cahoy et al., 2006).”
(Emphasis added.)
What this diagram tells us:
is that the actual (environmental) lapse rate between ~2 and 10 km above the surface lies somewhere between -2 and -3 K/km on average, that is, as on Earth, well below the ideal “dry adiabatic lapse rate”. Furthermore, we can readily see proof of what Barlow discusses above, the fact that the lapse rate in the lower 1.5-2 km of the Martian atmosphere is only clearly negative during the day; at night, it is just as clearly positive, a result of the strong near-surface temperature inversions. The daily average ([day+night]/2), then, rather ends up more or less equal to 0 K/km. IOW: On Mars, the temperature at the actual surface is no higher – on average! – than it is at an atmospheric level 1500m above the ground.
Nikolov & Zeller’s estimated T_s value is thus, based on this flawed “-4.3K/km-lapse-rate-from-the-surface-up” premise of theirs alone, most likely 6-7 degrees too low.
They also introduce other strange and simplistic guesstimates about certain relationships to reach half-hearted conclusions that still seem way too confident, bordering on pure handwaving. A good example is the one about ‘determining’ a global temperature average as somehow the mean simply of two specific latitudinal averages – all you need to do is pick the right two latitudes (and N&Z appear to know them already), and the global average magically follows …
Thanks Okulaer. I’ll leave Ned to deal with the bulk of your commentary, and restrict myself to one point.
you mention the lack of lapse rate, on average, to an altitude of 1.5km. However, looking at the profiles you’ve kindly provided, the average of both day and night lapse rates to 40km is somewhere much nearer to Ned and Karl’s estimate.
By the way, they have indeed worked out at what latitude the average latitudinal temperature equals the global average temperature for airless bodies such as our Moon, and nearly airless bodies such as Mars. They have done so using a clear, precise and scientifically valid method, which you’ll get the chance to criticise after its publication.
”What’ll happen when the lateral air has been used up and there’s none left to fill the void left by air convecting to high altitude?”
You haven’t shown you’ve watched the convection videos, they show why no one asphyxiates from used up fluid. There is no lateral air (fluid) ever used up, the winds continuously circle laterally about the center of the lo and hi (power source is the sun). The winds by and large stop blowing when there is no lateral pressure gradient like at the center of the system & between systems. No worries, we’re all not gonna asphyxiate since the air is well mixed by the horizontal N,E,W,S winds.
Point your RH thumb up in NH lo pressure systems and curl your fingers, that’s how the winds move. You can tell if the center of the system is approaching or already passed by noticing the direction of the winds & compare to the direction of your finger curls. Point your thumb down for passing hi pressure systems & do the same.
”Maybe this was too brief for your understanding?”
Not at all. There are no descending air parcels observed hitting us on the head, nothing forces them down since they are hydrostatic not hydrodynamic, the atm. density gradient is by and large horizontal. Watch the convection videos. Not much descending fluid since the parcels spread out horizontally when they achieve ambient, since as I pointed out: though there is an enormous amount of PE very little PE is available to convert to KE (see CAPE) in a mostly hydrostatic atm.
”There isn’t. Stop introducing red herrings right now.”
Good, you agree no contraction for earth atm.
A continuously contracting atm. adds energy to the atm. system as a force m*g moves through delta h (m*g*delta h). I’m curious then what continuous adding of force to an atm. is N&Z talking about if you agree there is no atm. contraction (so no delta h) p. 12: “Adding a force such as gas pressure to a physical system inevitably boosts the internal kinetic energy and raises its temperature, a process known in thermodynamics as compression heating.”
Trick: You haven’t shown you’ve watched the convection videos, they show why no one asphyxiates from used up fluid. There is no lateral air (fluid) ever used up, the winds continuously circle laterally about the center of the lo and hi (power source is the sun). The winds by and large stop blowing when there is no lateral pressure gradient like at the center of the system & between systems. No worries, we’re all not gonna asphyxiate since the air is well mixed by the horizontal N,E,W,S winds.
Trick is in denial of simple and obvious observations such as the wel observed rapid updraught and buildup of massive cumulonimbus clouds which evidence large volumes of air rising to the upper troposphere. Rising air expands as it decompresses and forces other air at high altitude back downwards towards surface, adiabatically heating as it descends. Notably, as I documented and evidenced earlier, at the Hadley/Ferrell cell boundary. This is not an occasional weather event, but the daily engine of tropical energy transfer.
I note also that Trick has made no response to or critique of the points I made about adiabatically heated descending air impeding the rate of conduction of heat from surface to air, and the fact that this must force the surface to a higher temperature than it would otherwise be at.
Air pressure raises Earth’s surface temperature not by “creating heat”, but by impeding the transfer of the Sun’s incoming energy back to space, and by impeding the rate of the Sun’s evaporation of surface moisture.
Trick: I’m curious then what continuous adding of force to an atm. is N&Z talking about if you agree there is no atm. contraction (so no delta h) p. 12: “Adding a force such as gas pressure to a physical system inevitably boosts the internal kinetic energy and raises its temperature, a process known in thermodynamics as compression heating.”
Take a perfectly insulated vessel and compress the air inside it. It rises to a higher temperature, and so long as the insulation is perfect, it stays at that higher temperature, no further or ongoing compression required. Mike Flynn says the vessel cools to the ambient surroundings. But when the entire lower atmosphere is the gas being compressed and the vessel wall is the Earth’s surface against which the gas is compressed by gravity, there is no ‘ambient surrounding’ to lose heat to. To be sure, energy escapes to space, but this is balanced by the amount of energy coming in from space. 240 in, 240 out.
The mechanisms I have described above are the reason there is a higher surface temperature ,(Ts), than seen with no atmosphere (Tna).
Impedance of evaporation doesn’t happen with no atmosphere.
Nor does impedance of energy transfer from surface due to the compression heating of descending air. Because there’s no air to be compressed.
If you can make a planet absorb more sunlight, this will make the planet warmer.
Earth absorbs a lot of sunlight, Venus does not absorb more sunlight than Earth does and Venus has higher surface air temperature as compared to Earth.And there are other factors which cause a planet to be warmer other than the amount of sunlight that is absorbed.
Venus doesn’t absorb much sunlight and one could easily increase the amount of sunlight Venus absorbs, unlike Earth which absorbs a lot sunlight and would more difficult to improve how much sunlight it absorbs.
So how could Venus absorb more sunlight? (And you might also ask why does Earth absorb so much sunlight?)
Venus doesn’t absorb much sunlight because it’s covered by clouds.
If the clouds were removed, Venus might absorb more sunlight. But what would work better is by replacing the clouds with something which absorbed sunlight better than than the clouds.
One might also claim, that Venus proves that some kind of clouds cause a planet to absorb less sunlight as compared to some other type of clouds or something else floating in the sky.
One could ask, if Venus clouds were replaced Earth’s water clouds, would the water clouds absorb more or less sunlight?
It could be a complicated question. One part of it that makes it complicated is that water may restricted less as compared to the sulfuric clouds. Or it would everywhere in the atmosphere and extending to the rocky surface.
Anyhow, you don’t need to replace Venus clouds with other kinds of clouds. You could replace them with an asphalt parking lots or floating swimming pools. On top of balloons, or just have balloons, say dark colored balloons which also good at absorbing sunlight.
Any kind of surface, which was not highly reflective to sunlight, is going to be hot. Making any kind of surface not be hot is difficult. And also making any kind of cloud not be warm is difficult.
But make things cooler and absorb a lot of energy, a big balloon is easier than a small balloon.
Or where you would be in the atmosphere, travels around the planet every 4 to 5 days, so if had a lot of thermal mass, it would heat up during daylight and cool down during the night.
Therefore a large balloon could have less wide swings in temperature, and absorb more sunlight than a smaller balloon.
To understand the lapse rate google adiabatic compression. If you can’t run with the big dogs you had best stay on the porch.
tb, thanks for being a good sport in this discussion. Only if the entire atm. is compressed does it acqure additional thermal energy. The top of the convecting column equilibrates with surroundings so becomes indistinguishable from the rest of the atm., same p,t, density which is why no descending parcels can be uniquely dentified, just have the general circulation as in the convection videos.
–“Mike Flynn says the vessel cools to the ambient surroundings. But when the entire lower atmosphere is the gas being compressed and the vessel wall is the Earth’s surface against which the gas is compressed by gravity, there is no ‘ambient surrounding’ to lose heat to. To be sure, energy escapes to space, but this is balanced by the amount of energy coming in from space. 240 in, 240 out.”–
I like that explanation.
But I think with Venus, the air is warmed it level of clouds, and that is why Venus surface air is hotter than it should be from the Sun energy.
Or Earth surface air is not warmer than it should be from sunlight, which indicates to me that not much heating of air occurs at Earth cloud levels. And I would guess the hottest Earth surface air as ever achieved is when the Mediterranean sea dried up, and most of Earth air was (and is) warmed up at sea level.
Trick my old friend, what goes up, must come down. Here’s where you went wrong:
You said: There are no descending air parcels observed hitting us on the head, nothing forces them down since they are hydrostatic not hydrodynamic
This is mostly incorrect. The Sun and the gravity induced pressure gradient which facilitates buoyancy forces high altitude air down, though as you say, not as discrete ‘parcels’. Let me explain how.
The Sun’s energy heats the surface. The surface conducts that sensible heat and water vapour (carrying lots of latent heat) to the air. This buoyant, (and therefore hydrodynamic) air convects rapidly to the top of the troposphere (and even beyond, as rapidly building cumulus pierces the tropopause). That air expands as it rises into the lower pressure high altitude regime. This expanded rising air DISPLACES cold, dry high altitude air DOWNWARDS, where it re-equilibriates the hydrostatic pressure gradient enforced by the iron grip of gravity. As it descends, it is compressed in the pressure gradient and heats adiabatically.
Now, I understand where your confusion has arisen, because when it reaches surface, the descended, adiabatically heated air then ADVECTS horizontally (as described by your general circulation videos) into the relatively lower pressure regions formed where convection has taken place, promoting and absorbing further evaporation, and thereby becoming more buoyant as it travels. The cycle then repeats.
Re.: tallbloke says:
January 30, 2019 at 6:44 am
All sailboat sailors know this. I.e. changing wind during day and night due to solar heating of land, doldrums, passat wind etc. “Mike Flynn” should know it too.
Well, yes. I’ve kicked “Mike Flynn” out so we can proceed with reasonable scientific discussion of real meteorological and planetary-atmospheric phenomena.
We had to progress beyond the thermodynamic kindergarten of aqualung bottles and car tyres at some point.
It is interesting that the environmental lapse rate on Mars (2-3k/km) is less than the adiabatic lapse rate (4.3k/km) i.e. an increase in potential temperature of at least 2.3k/km with height above the surface.
An increase in potential temperature with height on Earth is put down to the release of latent heat.
As water vapour is just a trace gas on Mars, is this reduction of the adiabatic lapse rate due to release of latent heat of carbon dioxide or the ability of a radiative gas to radiate energy from warmer lower levels to higher cooler levels and thus shrink the thermal gradient from both ends?
https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.1926.0065
Interesting questions Pablo.
From Okulaer’s earlier comment, quoting Barlow:
“Nighttime temperatures can drop low enough to cause condensation of atmospheric water vapor, producing the hazes and fog commonly seen in the early morning hours.”
So even though water is scarce on Mars, there’s enough of it to produce significant meteorological effects it seems.
tb 6:44am, when the convection videos are observed, at the top of the obvious convective column the fluid spreads out mostly laterally high up as it has equilibrated with surroundings in p,t,density.
The replacement fluid has moved in laterally at surface ambient(0), and ambient(z) along the natural lapse all the way up to the altitude the rising fluid is fully equilibrated. I am only trying to put into words what is observed. The replacement fluid is what is meant by general circulation(z) which neither heats nor cools at ambient.
When you write a displacement of cold air you really mean a displacement of ambient air.
In a mostly hydrostatic atm. that replacement fluid is neutral buoyant at surface and neutral buoyant all along the lapse at the height the convection ceased. There is not much downward movement after convection ceases just mostly horizontal movement (geostrophic winds) at neutral buoyancy in a mostly hydrostatic atm., the density is stratified horizontal outside the convective column. I like your word hydrodynamic though for convection. This is how the geostrophic winds originate in hi and lo pressure systems.
If interested enough, I suggest find a text of your choice to read about CAPE for a more technical discussion of what is observed in the convection videos and in earth atm. local sounding records. Here is my suggestion, an early paper on the subject of convective available potential energy (CAPE) for which the full text is free, my wording just is not as specific & technical as the author’s:
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.2153-3490.1955.tb01148.x
I have more if interested.
Thanks for the links and vids Trick, I don’t have much time for reading science papers at the moment due to my day job securing Brexit, but I’ll try to catch up.
What goes up must come down. It’s the law.
‘ambient’ at the tropopause is 216K
Ascending air cools at the environmental lapse rate.
Descending air is dry, and warms at the dry adiabatic lapse rate
MET office confirms descending polar air can raise near surface T up to 50C in a matter of days. Food for thought.
“Descending air is dry, and warms at the dry adiabatic lapse rate.”
What fluid convects up was warmed greater than ambient T by a source burning a fuel, what replaces the rising fluid is at ambient, has no fuel source to cool it below ambient. There is no descending air column observed in the videos, there is horizontal air moving in at ambient observed to replace the rising convective air. The general circulation is net neither rising nor descending for earth or in the videos as the atm. or fluid tank is not continuously contracting nor expanding. This is what is meant by mostly hydrostatic in the fluid tank and in earth atm.
Your progress in learning/studying meteorology is being impacted by brexit. Recommend pick it up again after March 29.
There is no descending air column observed in the videos,
Yes. We already agreed air doesn’t descend in columns. Descend it must though, to make way for convective columns which most certainly are observed both visually in building cloud heads, and viscerally in glider aircraft riding thermals.
there is horizontal air moving in at ambient observed to replace the rising convective air. The general circulation is net neither rising nor descending
Of course it’s not net rising or descending! This is because the same amount has to come down as goes up!
there is horizontal air moving in at ambient observed to replace the rising convective air
And as I pointed out above, some of that replacement air comes down first and then advects horizontally.
Right, back to work. See you later. 🙂
”Yes. We already agreed air doesn’t descend in columns.”.
Cool.
”some of that replacement air comes down first and then advects horizontally.”
As discussed in “Available Potential Energy and the Maintenance of the General Circulation” paper because the atm. is not 100% hydrostatic. The non-convecting fluid circulates at ambient conditions in the general circulation of the fluid (water) tank and in the atm. This starts to show how convection is different than the general circulation & how much PE is available to convert to KE in storms and other processes (not very much).
NB: Your video does not once mention the word convection, it is all about another process that “tickles the cloud tops” from above by converting a bit of total PE into KE.
I’m beginning to see how I can calculate a rough engineering estimate of the magnitude of the evaporation impedance effect I outlined some initial calcs for yesterday. After that, we’ll see how much is left of the ~90K thermal enhancement of the Earth’s surface temperature compared to the Moon’s to be accounted for. I expect the conduction impedance effect to be the smaller of the two pressure based mechanisms I’ve identified so far.
tallbloke says, January 29, 2019 at 7:35 pm:
Not really. They’re rather pretty close to the fairly well-known mean value of Mars’s actually observed (environmental) tropospheric lapse rate, which is -2.5K/km, not -4.3K/km, which is the DALR on Mars, and which is only approached within columns of air where distinct dry convection is taking place, as pointed out by Barlow. Below ~1.5-2 km above the surface, the average lapse rate is reduced to more or less 0 K/km because of the strong inversions that prevail each night. And N&Z’s failed assumption is precisely about this lowermost layer of the Martian atmosphere, in trying to extrapolate the average temperatures measured by the Viking landers up to the datum level of their respective latitudes.
Doesn’t sound too convincing to me, I must say. We do have global Mars T_s data, after all, collected by various satellite-borne instruments spanning quite a few years by now. And they tell a somewhat different story, a slightly warmer one, that is. The Martian global average surface temperature seems to lie somewhere between 202 and 204 Kelvin, surface emissivity taken into account. Sure, it could still possibly be slightly colder than this. Or slightly warmer. But hardly 12-14 degrees colder. On a global annual average … If N&Z want to be serious about their claim, which is an extraordinary one, I expect to see extraordinary evidence. If they do somehow manage to produce such evidence, however, I’ll be first in line to congratulate them …!
Pablo says, January 30, 2019 at 10:04 am:
Mostly to do with aerosol particles suspended in the atmosphere being heated by the Sun, it seems:
http://www.lpl.arizona.edu/~griffith/PTYS517/marsatmosphere.pdf (referring to Haberle, 2002)
Okulaer: We do have global Mars T_s data, after all, collected by various satellite-borne instruments spanning quite a few years by now. And they tell a somewhat different story, a slightly warmer one, that is.
Shirley et al’s equatorial data as quoted by N&Z:
For highlands (≈5 km above Datum), the near-surface temperature appears to be around 200 K, while for lowlands (≈2.5 km below Datum) it is ≈211 K.
N&Z’s conclusion: Since most of Mars’ equatorial region lies above Datum, it is likely that Mars’ equatorial MAT would be lower than 205.5 K and close to our independent estimate of ≈203 K based on Curiosity Rover measurements.
Two points arise from this.
1. 11K over a 7.5km vertical separation supports your comment on near surface lapse rates.
2. An equatorial average around 203K would indicate a global average under 200K.
tallbloke says: January 30, 2019 at 3:24 pm
While catching up, suggest to start with the basics:
ascending air cools at the DALR, until it passes its condensation level, from then on the rising air cools at the MALR.
Descending air warms at the MALR, until all water is evaporated, from then on the descending air warms at the DALR.
These are all adiabatic processes. Makes me wonder who is confusing diabatic and adiabatic processes.
Ben 9:45pm: ”These are all adiabatic processes.”
No real process is adiabatic.
Convectively rising air (observed as glider VFR pilot nirvana in clear air so no condensation) is a diabatic process as the parcel of air was warmed above ground level ambient from a source burning a fuel & becomes positively buoyant. The warmed surface air naturally rises (the velocity is calculable), replaced by ambient surface air horizontally and, above the surface, ambient air also horizontally along the natural lapse rate & all the while losing its thermal energy above ambient until the parcel equilibrates T,P,density again with ambient at a higher altitude and ~remains there (now neutral buoyant) diffusing at ambient.
This convective diabatic process helps drive the ~adiabatic (since frictional losses occur) global general circulation cells. If you are interested “To understand the maintenance of the energy of the general circulation” see sec. 5, p. 165 of the free paper I linked for tallbloke 3:09pm.
Trick says: Jauary 30, 2019 at 10:58 pm
Agree, the process is assumed to be adiabatic so we have a simple formula for the (dry) adiabatic lapse rate.
The warming of a thermal at the surface is obviously diabatic. Once the thermal leaves the ground, the warming stops and the RISING air now cools according the DALR, until a cloud starts to form (those nice puffy Cumulus clouds) and the air now cools according the MALR, where condensation internally warms the thermal and the rising continues.
@okulaer,
Thanks for those interesting graphs concerning Mars. The surface pressure on Mars is ~0.06 bar. According to Robinson & Catling it takes a pressure in excess of 0.1 bar to qualify as a “troposphere”.
Thus the atmosphere on Mars could be called a “stratosphere”. While convection dominates in tropospheres, radiation dominates in stratospheres.
Because radiation dominates heat transfer in stratospheres the ALR (Adiabatic Lapse Rate) is usually positive.
The ALR for Mars is mostly anomalous (negative) except for regions within 3 km of the surface. There are six worlds in our solar system that have stratospheres with positive ALRs and two with negative ALRs (Venus and Mars). Robinson & Catling explain why carbon dioxide causes anomalous ALRs on Venus but they have nothing to say about Mars:
Click to access Robinson2014_0.1bar_Tropopause.pdf
TB says re Mars: An equatorial average around 203K would indicate a global average under 200K.
Indeed…
Ben 6:45am: ”the RISING air now cools according the DALR, until a cloud starts to form”
Any convecting rising air parcel is still buoyant thus the parcel is at a T above, density below, the natural lapse surroundings at each z, so that parcel has not yet cooled to ambient. The parcel does not necessarily rise high enough to form a cloud, depends in part on the parcel’s initial ascent velocity* which can be calculated from the convective available PE (CAPE) formula. Entrainment also enters the picture to make the diabatic cooling process even more complicated & thus interesting.
Of course, storms were an early interest in meteorology so to enable predictions (as today!). There is a little-known thumb rule over 175 years old (Philosophy of Storms 1841 by Espy): “The bases of all clouds forming by the cold of diminishing pressure from up moving columns of (tallbloke’s blue) air, will be about as many hundred yards high as the dew point in degrees is below the temperature of the air at that time.” Today’s concept of CAPE yields 75 yards in place of Espy’s much earlier 100 yards.
A consequence of thermodynamic properties of water and air, the only reason clouds can even form on convective parcel ascent is that the temperature of a convecting parcel happens to decrease more rapidly than its dew point. This all leads to studying the concept of the lifting-condensation level (LCL) if you are interested. LCL being the level to which a convecting parcel of air would be lifted dry to reach a relative humidity of 100%. That level is a unique function of the parcel’s temperature and humidity.
Rising columns of convecting parcels are thus a bit more complicated than tallbloke’s cartoon of blue arrows marching upwards showing “expansion cooling”.
*observed by irritated airplane pilots and their sometimes-queasy passengers.
gc: ”Thus the atmosphere on Mars could be called a “stratosphere”.”
At the tropopause, convection mostly* ceases because the fluid becomes warmed from above instead of below in a gravity field like in the troposphere. Mars dust devils observed attest to tropospheric convection still existing at global avg. 6mbar pressure below R&C 100mbar to 200mbar observations so R&C just throw up their hands and surrender to Mars.
*parcel vertical ascent velocity sometimes causes the tops of earthian clouds to extend into the stratosphere from their momentum as they cauliflower out. Updrafts in usual Texas storms might be around 60m/sec where max. earthian updrafts observed around 115m/sec.
re. Trick’s reply to Ben…
Which points to the observation of a “dry” adiabatic lapse rate within the boundary layer (i.e. constant pt with height) being due to a mixing by turbulence and friction rather than any rising of parcels to reach a dew point.
parcel vertical ascent velocity sometimes causes the tops of earthian clouds to extend into the stratosphere from their momentum as they cauliflower out. Updrafts in usual Texas storms might be around 60m/sec where max. earthian updrafts observed around 115m/sec.
Not just in texas either, but right around the ITCZ too. This what drives the Earth’s general circulation in the tropical zones.
Back when we first started ths ATE treck, we had fiddlers telling us we needed to know as much Meteorology as them, so hey might argue angels on a pin rather than the real case.
Now, with N and Z’s use of a more sophisticated analytic system, they badger us again when they actually lack perception of what Physics is, at heart, about. That is, the real nature and Mechanics of, in this case, atmospheres and solar system body energetics. Tropospheric or not.
Take a deep breath boys, and turn your thinking on its head That is what I do when seeking to solve seemingly intractable problems of Applied Science. What you find out is not so, helps get to what is. For instance, what is a gas at heart and how does it differ in basic properties from other phases? What does it do when thermalised? Is radiation a primal force or an effect? Etcetera, doceo – I teach, I learn …….. Brett
@Trick,
“Mars dust devils observed attest to tropospheric convection still existing at global avg. 6mbar pressure below R&C 100mbar to 200mbar observations so R&C just throw up their hands and surrender to Mars.”
I agree. Take another look at okulaer’s comment:
Note that some of the curves have regions with positive lapse rates. The Robinson & Catling model can’t explain that.
gallopingcamel says: January 31, 2019 at 8:01 am
– What has radiation to do with the ADIABATIC lapse rate?
– How can the ALR be negative in an atmosphere that is (mostly) in Hydrostatic Equilibrium?
Trick says: January 31, 2019 at 3:04 pm
Thanks for the long reply. Travelling at the moment with irregular connections.
A parcel rises as long as its density is lower than the density of the surrounding air. Dry convection dies out pretty quickly, it takes cloudforming (= condensation) to reduce the cooling rate of the rising air so it can stay warmer (= less dense) than the surrounding air. Don’think initial ascent velocity is very relevant. The temperature profile of the surrounding air is the deciding factor for convection.
CAPE is basically the difference between the decreasing temperature of the rising parcel versus the actual temperature profile of the surrounding air.
Ascent velocity can be seen in Thunderstorms. When the rising air passes its neutral buoyancy level at high speed, it will decelerate and fall back, forming the anvil.
I’m familiar with LCL etc.
LCL, CAPE etc all nicely shown in:
Click to access 09%20Convective%20forecasting.pdf
tallbloke says: January 31, 2019 at 6:08 pm
Do you actually believe that a few CB’s around the equator drive the Hadley circulation some 3000 km towards 30 N/S and suck air back in as the Trade winds?
Ben: Acronyms. What are CB’s? Convective ______’s ? Cumulus ______’s ?
It’s interesting that Earth has large scale structures like the Hadley and Ferrel cells, whereas Venus doesn’t. This may well be pressure related. Jupiter seems to have lots of them, but is much colder of course.
So I’m not sure the distance is relevant. What is relevant is the convection itself. Lot’s of that happening all around the equator, and over temperature landmass too.
Ben 11:21am, ”Don’think initial ascent velocity is very relevant.”
Ascent velocity IS important to determine if rising convective parcels are likely to develop stormy weather as discussed in your great set of slides. S*(CAPE)^1/2 is related to updraft speed, search: Vorticity Generation Parameter
Initial max. attainable updraft speed = (2*CAPE)^1/2 which if large enough momentum allows the rising convective parcel punch through to higher altitudes at the usual horizontal inversion layers up around 600-800mb as shown in the various P-T soundings. Especially interesting is how the inversion layers reverse with daily sun warming from the Oklahoma morning sounding to PM sounding, search: morning (1200 UTC) soundings.
If the updraft speed isn’t large enough (not enough convective available PE i.e. CAPE) convection ceases at ambient near the lower level of free convection (lower boundary of neutral buoyancy LNB). This would mean little vorticity and no storm clouds develop in higher 100% RH layers as discussed in the presentation: “CAPE is a reasonable predictor to separate hail producing or tornado producing supercells from ordinary thunderstorms, and with very high values (greater than 2500), has predictive value for separating supercells that produce tornadoes from those that do not.”
This is another means to learn how convective updraft rising diabatic columns (tallbloke’s 1:48pm blue arrows) cease at some altitude where parcels diffuse at ambient so differ from the general circulation at ambient which is ~adiabatic (ignoring frictional losses shown in tallbloke’s 1:48pm red arrows).
TB – re: It’s interesting that Earth has large scale structures like the Hadley and Ferrel cells, whereas Venus doesn’t.
Someone (David Esker) theorises that Venus has a one-cell system whereas Earth has three (Hadley, Ferrer, polar). Search the link for ‘The Mesozoic Paleoclimate Paradox’ and scroll down, or just look for ‘one cell’:
https://dinosaurtheory.com/thick_atmosphere.html
Esker: A primary reason there is almost no variation in temperature over the entire surface of Venus is because Venus has an extremely efficient atmospheric convection current system that uniformly distributes the radiation / thermal energy coming from the Sun. With such a thick atmosphere, there is only one convection cell in each hemisphere carrying the heat from the equator to the one or the other pole. This one cell system is much more effective than the Earth’s present-day three cell system in distributing heat from the lower latitudes to the higher latitudes.
– – –
Btw I’m not saying this must be right, but maybe worth discussing 🙂
The production of irrelevant verbiage from the usual Antis show strongly that they did not closely study nor understand N+Z’s Conclusions. Why am I not surprised? Nope, Meteorological games will not get you there. They are minor effects just like spectra, never causes. But you have been told before…….. What Maxwell figured easily long ago. Should be no dishonour to admit our mental deficits in such company. Scientific Method is the toolset invented to equalise us more or less. Please try it. Brett
@ Rog
I left two messages at Suggestions, one yesterday, one just now, but nothing has appeared.
[mod] salvaged from spam bin, not sure what happened
@Ben Wouters,
“– What has radiation to do with the ADIABATIC lapse rate?”
Within planetary tropospheres thanks to collision broadening absorption of thermal radiation is proportional to the square of the pressure which means that radiation works just like convection to set up a temperature gradient (aka the Adiabatic Lapse Rate).
In Planetary stratospheres the absorption of radiation is directly proportional to the pressure which means that energy can more easily leave the system which is therefore no longer “Adiabatic”.
Thermodynamics is not one of my strengths but I apply the term “adiabatic” to processes without the exchange of heat between system and environment. You can find the equations underlying the Robinson & Catling radiative-convective model here:
Click to access Robinson2014_0.1bar_Tropopause.pdf
Does the new Cold Night time temperature found by the Chinese affect N & Z’s calculations for the moon?
A C: Tell us more. Where’s the data?
TB: see today’s blog post…
– – –
Unrelated – Lucy Skywalker has msg for you:
tallbloke says: February 1, 2019 at 11:49 am
Seeing you using ITCZ it seemed OK to use related Acronyms.
CB stands for Cumulonimbus. Is a well developed rain or thunderstorm.
CB’s have only local influence. (few 10s of kilometers)
They don’t drive Earth’s general circulation as you stated.
This is an entirely different mechanism (uneven surface heating causing uneven expansion of the atmosphere (Hydrostatic Equilibrium))
Difference between Earth, Venus and Jupiter is their rotation speed.
The higher that speed the higher the Coriolis Effect, thus the sooner a General Circulation will break down in sub-circulations.
Trick says: February 1, 2019 at 2:11 pm
It’s easy to come up with a temperature profile that will allow convection to reach high altitudes without generating thunderstorm activity (eg Towering Cumulus) at low vertical speeds.
Very confusing text. How is a convective updraft rising column diabatic?
(I do agree no real process is 100% adiabatic)
The general circulation is a typical diabatic process.
Sun heating the surface uneven between Equator and Poles.
Atmosphere expands more with higher surface temperature, creating pressure differences that drive the general circulation.
gallopingcamel says: February 1, 2019 at 11:37 pm
Convection does not set up a temperature gradient. The process is considered to be Adiabatic.
Convection stops when the temperature of the rising air is equal to that of the surrounding air.
The temperature profile (gradient) of the atmosphere is usually referred to as Environmental Lapse rate.
The two Adiabatic Lapse Rates (Dry and Moist) are exclusively valid for rising or sinking air within an atmosphere that is in Hydrostatic Equllibrium.
“How is a convective updraft rising column diabatic?”
The rising convective parcel temperature is above the local ambient T(z) along the natural lapse rate or it wouldn’t be bouyant/rising. So the parcel is diabatic exchanging thermodynamic internal energy out with its surroundings by cooling faster than its dew point until it reaches ambient temperature(z). No cloud forms if this equilibration level z is below 100% relative humidity, the intial velocity (from CAPE) was not high enough in that situation.
”The general circulation is a typical diabatic process.”
No, the general circulation shown by tb 6:08pm is maintained at local ambient. Convective parcels are above local ambient temperature thus diabatic. This whole discussion is to show the difference between general circulation and convection. Again, if you are interested “To understand the maintenance of the energy of the general circulation” see sec. 5, p. 165 of the free paper I linked for tallbloke 3:09pm.
tallbloke says, January 30, 2019 at 9:29 pm:
I think you (and N&Z) need to take a closer look at those Shirley et al. profiles and read what is actually being said about them. Again it’s this kind of sloppy argumentation that weakens my confidence in N&Z’s alleged “findings” almost to the point of disbelief.
Click to access shirley_paris2011.pdf
Study Figs. 4 and 5, and read carefully the accompanying text. What are we actually being presented with here?
Problem is, the equatorial (annual/circumglobal) average is really FAR higher than 203K.
I’ve spent some time now delving into this issue, and in the end it seems pretty clear that – with ALL the data taken into account, that is, weighted globally and annually – Mars’s T_s is not even remotely as cold as 190K. Until very recently, I was convinced it lay somewhere around 202-204 K, based on papers like Bandfield et al., 2013, but I know realise that even this estimate is most likely several degrees too low. I was simply too quick in concluding, just like you are now, and N&Z have been. I should – and this, after all, should be a golden rule to anyone and everyone – have paid much closer attention to what the data I looked at actually represented. And one thing’s for sure, they did NOT (!) represent the temperatures of a full Martian year. That was my mistake then, and it is your mistake now …
At this point, my best estimate regarding the (globally/annually averaged) T_s of The Red Planet would be ~209 K in brightness temperature and 211-212 K in “real” temperature.
Bandfield et al., 2013:
Click to access bandfield_mcs_tes.pdf
Determining a Martian global/annual average T_s is ultimately a pretty complex affair, it turns out. 1) The NH and SH are wildly dissimilar in mean altitude, and 2) Mars’s orbit around the Sun is much more eccentric than Earth’s, which means that seasonal differences, especially when comparing the seasons of the NH and the SH, are much more pronounced. Aphelion occurs at the start of the NH summer and SH winter, while perihelion happens at the start of the SH summer and NH winter. This makes a difference …!
Max daily temps, NH summer/winter:
I also found this recent textbook (Haberle (Smith), 2017) on this very subject, which appears to make a case for an average global/annual T_s on Mars equal to 215.7 K, a value I, however, find suspiciously high (for one thing, they seem to extrapolate the negative average lapse rate all the way down to the surface):
https://books.google.no/books?id=bokmDwAAQBAJ&pg=PA42&lpg=PA42&dq=4+-+Thermal+Structure+and+Composition+mars+smith+haberle&source=bl&ots=9UHFCwQWGE&sig=ACfU3U3I_RznAs_QIlpOr7ogj5GrCZwzjg&hl=no&sa=X&ved=2ahUKEwjV1tXyzpvgAhXvp4sKHY45BKEQ6AEwB3oECAYQAQ#v=onepage&q&f=false
(Fig. 4.11 and Table 4.3, p.52)
Kristian 4:23pm: ”..which appears to make a case for an average global/annual T_s on Mars equal to 215.7 K…”
I observe your T_s notation is not consistent with Haberle’s. I suggest you obtain his note in Icarus 223 (2013) p. 619-620 to learn the consistent T notation to eliminate readers notation befuddlement trying to make sense of your comment.
https://www.sciencedirect.com/science/article/abs/pii/S0019103513000055
Haberle 2013 Table 1:
Mars clear atm. annual avg. global mean surface temperature: 200.92K
Mars dusty atm. annual avg. global mean surface temperature: 203.65K
—-
Mars effective surface temperature Tse which is the 4th root of the annual and globally averaged value of (Ts)^4:
Mars clear atm. Tse: 214.87K
Mars dusty atm. Tse: 214.43K
Haberle explains the proper method to compute Mars GHE is to subtract the temperature Te at which a blackbody radiates away the energy it absorbs from Mars Tse.
Mars clear atm. GHE: 214.87K – 209.74K = 5.13K
Mars dusty atm. GHE: 214.43K – 209.28K = 5.15K
——
Haberle explains this may seem obvious but the distinction is often not recognized in the literature.
Haberle: “it is often stated that the mean annual surface temperature on Mars is 210-215K, when this is really the mean annual effective temperature. Mean annual surface temperatures are closer to 200K”.
If you really want to communicate & reduce at least this reader’s befuddlement from your comment, I suggest recognizing/using the notation distinctions and write your comment consistent with those Haberle temperature notations.
—-
NB1: Surface emissivity set to 1.0 at all grid points
NB2: Book page 52 was not immediately available on the net, I may try to get a copy when time permits. That book appears interesting resource.
Kristian again: ”Again it’s this kind of sloppy argumentation that weakens my confidence in N&Z’s alleged “findings” almost to the point of disbelief.”
I agree with that.
N&Z 2014 defines atmospheric thermal enhancement ATE = GHE then in 2017 they start to use “atmospheric thermal effect” as something different than 2014’s ATE so commenters use both abbreviations interchangeably when they are different.
N&Z table of NASA temperatures does not make clear Haberle’s noted difference in solar object mean Ts, Tse, Te so N&Z prose becomes very confusing as to which temperature they really mean. For Mars, Haberle shows that’s a source of ~15K confusion! Haberle is correct that the differences may seem obvious but the “obvious” distinction is not recognized in N&Z 2017 paper.
N&Z write in App. B their “Adjusting” “inferred” “adjusted” in situ data for 190.56K GMAT Tm=Ts “agrees quite well with spherically integrated brightness temperatures of Mars retrieved from remote microwave observations during the late 1960s and early 1970s [85-87]” thus would be Haberle’s Te.
Trying to trace thru N&Z mixing of temperatures in App. B to map them to Haberle’s (mean Ts, Tse, Te) physically correct work – I’ll leave to others.
Trick,
Thanks! That’s very interesting. So, through some weirdly looped back-door pathway, it turns out my first estimate (202-204 K) was more or less correct, after all. Hmm. Now I’m befuddled …!
Either way, it seems to be finally acknowledged by now that Mars’s real globally, annually averaged T_s (based on actual measurements) is indeed several degrees lower than the planet’s T_e, and not higher, as most sources still tend to claim. And that it is only a conceptual (modelled) quantity called T_se, which is essentially just a back-engineered mathematical abstraction, not a real thing, that is higher …
Ben W: Atmosphere expands more with higher surface temperature, creating pressure differences that drive the general circulation.
Yes, that was what I was pointing out to Trick a couple of days ago.Jan 30 6.44am
The Sun’s energy heats the surface. The surface conducts that sensible heat and water vapour (carrying lots of latent heat) to the air. This buoyant, (and therefore hydrodynamic) air convects rapidly to the top of the troposphere (and even beyond, as rapidly building cumulus pierces the tropopause). That air expands as it rises into the lower pressure high altitude regime. This expanded rising air DISPLACES cold, dry high altitude air DOWNWARDS, where it re-equilibriates the hydrostatic pressure gradient enforced by the iron grip of gravity.
Ben Wouters says, February 2, 2019 at 3:18 pm:
and,
Then I do wonder, Ben, how would you go about explaining the negative tropospheric temperature profile (the ELR)? Hydrostatic equilibrium itself couldn’t create it, after all …
tb: ”This buoyant, (and therefore hydrodynamic) air convects rapidly to the top of the troposphere (and even beyond, as rapidly building cumulus pierces the tropopause).”
Only if the convective available PE (CAPE) is high enough for the buoyant parcels to attain such a height. For the most part in earth’s mostly hydrostatic atm. this does not happen, there is not enough CAPE to drive most of the convecting cells that high. High convective available PE is a rarity like occurs in tornadoes, bad storms & known from soundings.
The general circulation is the great mass of air multi annual red and blue arrows shown in your 6:08pm which would also be the multi-annual red and blue arrows in your 1:48pm shown rising above the clouds. Because the general circulation is the great mass of air, almost by def. that circulating air is at ambient & not a tiny, local rising convective parcel which is higher T than ambient.
Again, when you are not too busy with Brexit, if you want “To understand the maintenance of the energy of the general circulation” see sec. 5, p. 165 of the free paper I linked 3:09pm.
—–
Kristian 10:14pm: ”Mars’s real globally, annually averaged T_s (based on actual measurements) is indeed several degrees lower than the planet’s T_e”
Yes about 8.82K lower clear sky including modern sparse actual thermometer in situ observations. However, Haberle concludes that is a “not correct” way to interpret Mars GHE. N&Z Mars GMAT follows the Haberle incorrect conclusion (p. 19 2nd para.*) but it’s difficult to tell which temperatures they really mean (Haberle Ts mean, Tse, Te) as their prose is not specific enough.
Haberle has the correct Mars GHE interpretation as Tse-Te = 5.13K for Mars clear sky GHE, which is “often quoted in the literature” but incorrectly stating from Ts mean – Te which creates the MAJOR confusion. Haberle also concludes the most representative Mars GHE is dusty atm. with clouds Tse-Te = 5.62K.
Following Haberle, their own cite, N&Z should have done the “Adjusting” “inferred” “adjusted” in situ data for 202.4 mars GMAT (dusty atm. with clouds). Since N&Z don’t provide the data or computer codes for the“Adjusting” “inferred” “adjusted” in situ data for 190.56K GMAT no one can replicate their work to compare N&Z methods to Haberle.
*N&Z 2017: ”Haberle [130] concluded that Mars’ mean global surface temperature is at least 8 K cooler than the planet’s effective radiating temperature.” which appears incorrect as Haberle really concludes “the correct statement is Mars effective surface temperature (Tse) is 5K warmer than Te. (Mars) mean surface temperature is actually much colder than its effective temperature” …as you write. Like my HS English teacher with a pronounced lisp taught me, in your writing: Be thpethific.
Who here understands Dimensional Analysis, and why N+Z use it for a ‘second bite of the apple? I sorta think it could be worth debating…… Brett
People might be interested in:
ftp://ftp.library.noaa.gov/docs.lib/htdocs/rescue/mwr/061/mwr-061-03-0061.pdf
..which discusses the reduction of the gravitational lapse rate via intermolecular radiation which “tends to bring the air of different levels to the same temperature.”
intermolecular radiation which “tends to bring the air of different levels to the same temperature.”
What about convection?
re. oldbrew’s comment…
Convection is most often confined to the boundary layer and the mixing of that air in daytime returns it to the “dry” lapse rate, but above that level the increase in potential temperature of 3.3ºC/km stays in place up to the tropopause. It just seems more logical to me that this is down to something more than latent heat.
Pablo: From your linked document, Page 1:
“The rate at which any particular sample (of air or surface) radiates depends mainly
on its absolute temperature”
As I said: Everything radiates according to its temperature.
The IPCC scientists would have us believe that everything’s temperature depends on its irradiation.
They have everything upside down and back to front, as usual.
Pablo wrote:
“Convection is most often confined to the boundary layer…”
Convection is pervasive and intrinsic. Small volumes of air move randomly, and interact more internally than between volumes. At STP and the 10 micron scale, it’s about 50 orders of magnitude more (~160 times the mean free path).
re. Q.Daniels
If convection was so pervasive then PT would be constant with height.
Lucy Skywalker: Thanks for your reply of Jan 22nd. It toook some finding.
Dimensional analysis is of course Maxwells too, by and large, and the intellectual ferment of those momentous foundation-laying decades needs remembering. Refresment on Graeff’s work could be in order? Brett
Mike Flynn: start with what gravity is really as I suggested or go home to your pines. Hint, coriolis too, re force. I see what you try to do but depth is required here….. Brett
Pablo,
When a gas gets expanded or compressed without an exchange of heat, ie convective mixing, the result is adiabatic. Also, approximately what is actually observed.
@Ben Wouters’
“Convection does not set up a temperature gradient. ”
You need to read Grant Petty’s book published in 2008 that explains heat transfer via tiny “parcels of air”:
https://sundogpublishingstore.myshopify.com/products/a-first-course-in-atmospheric-thermodynamics-g-w-petty
If that exceeds your boredom threshold I recommend “Physics of the Atmosphere” by Rodrigo Caballero.
My expertise is in quantum electro-optics rather than thermodynamics so I defer to real experts like Petty and Caballero or my ex-colleague at Duke (Robert E. Brown).
This thread is about Nikolov & Zeller who tell us that the primary variables determining planetary temperatures are PRESSURE and TOTAL SOLAR IRRADIANCE. The Robinson & Catling model says exactly the same thing while differing on some details.
The VCCS (Vast Consensus of Climate Scientists) says that Carbon Dioxide is the control know for climate. This idea is false and folks like Dr. Roy Spencer and Dr. Richard Lindzen should be smart enough to realize it.
I am impressed by okulaer who says that Albedo should matter.
Greetings “okulaer”. Apparently you are a geologist so what do you think of Ian Plimer’s book “Heaven & Earth”?
https://us.nicebooks.com/book/5255690?tag=GDSA&network=s&gclid=EAIaIQobChMIgYnq06uh4AIV4yCtBh0WigCGEAAYAyAAEgIeevD_BwE
N&Z know that albedo matters too. It’s around 0.12 for airless rocky planets. The fun starts when the hockey jockeys calculate the ‘greenhouse effect’ by comparing Earth’s surface temperature with a ‘no greenhouse gases’ Earth, but insist on keeping a 0.3 albedo in the calculation.
Utter nonsense.
tallbloke says: February 4, 2019 at 9:11 am
The hockey jockeys must think albedo causes itself 😐
Trick says: February 2, 2019 at 4:05 pm
Cooling is due to expansion into the lower pressure higher up.
The process is assumed to be adiabatic since:
– temperature differences are low
– duration of the process is short
– air is a poor conductor
– large volumes so relatively smal contact area with surrounding air.
https://en.wikipedia.org/wiki/Lapse_rate#Convection_and_adiabatic_expansion
Trick says: February 2, 2019 at 4:13 pm
General Circulation is from Equator to Poles. 3 distinctive cells.
eg the Hadley Circulation is from around the equator to around 30 N/S.
Air takes many hours/day to travel that distance. You claim this is a adiabatic process?
How about the backflow? The Tradewinds, they do not not pick up energy from the surface?
–This thread is about Nikolov & Zeller who tell us that the primary variables determining planetary temperatures are PRESSURE and TOTAL SOLAR IRRADIANCE. The Robinson & Catling model says exactly the same thing while differing on some details.–
Yes.
And it is sort of correct.
But I don’t think if replaced our atmosphere with higher density gas, and thereby increased
the weight and thereby it’s pressure, that it would have any significant warming effect.
Or that a high pressure greenhouse is warmer.
I think a large factor in regards to Venus is it’s
clouds and in regards to Earth, it’s ocean.
The idea of pressure being major factor, seems to cause one to look at changes in Earth pressure (or changes in solar output) in order to “understand” the changing temperatures of Earth.
We are living in an Ice Age and is because of low pressure and/or solar output?
What happens to Venus, if one mines the acid, so there is no more acid clouds?
The acid is not a bug, it’s a resource which can quickly depleted, and what effect will result if this acid is mostly removed?
And what happens if you add an ocean of water to Mars?
tallbloke says: February 2, 2019 at 11:30 pm
What you describe is convection, and than the violent type: thunderstorms.
The General Circulation is NOT driven by convection.
okulaer says: February 3, 2019 at 12:11 am
Obviously not.
Earth loses on average ~240 W/m^2 to space, of which ~40 W/m^2 comes directly from the surface.
So the atmosphere radiates ~200 W/m^2 to space that has to be replaced by direct solar heating or heating from the solar heated surface. This can happen by conduction/radiation/evaporation from the surface, turbulence / convection in the boundary layer and mostly radiation higher up.
Understanding how the atmospheric temperature profile and HE is maintained should be the subject of a discussion about planetary atmospheres.
Trick says: February 3, 2019 at 12:56 am
This site has CAPE data. Most of the world has no potential for any convection worth mentioning.
https://earth.nullschool.net/#current/wind/surface/level/anim=off/overlay=cape/orthographic=58.52,10.66,401/loc=39.482,51.741
gallopingcamel says: February 4, 2019 at 5:08 am
I believe I’m aware of the basics of parcels etc. One can’t discuss atmospheres without being aware of it being in Hydrostatic Equilibrium against gravity.
Understanding convection, Hadley Cell, Föhn effect etc etc. requires a thorough understanding of HE.
Even a star is in HE against its own gravity.
[…] Ben Wouters on Nikolov & Zeller: Reply to… […]
Ben W:“This site has CAPE data. Most of the world has no potential for any convection worth mentioning.”
Looking at South America and southern Africa, it seems that CAPE is very strong over rainforests, presumably due to the amount of water vapour being evaporated from the huge surface area of all those tree leaves (much greater evaporation area per km^2 than a km^2 of sea surface.
However, given the directly observable strength of daytime thermals over bare land surfaces such as the great deserts, and the assumption that nullschool.net is showing a 24hr average (or longer?), “no potential for any convection worth mentioning” seems wrong.
“One can’t discuss atmospheres without being aware of it being in Hydrostatic Equilibrium against gravity.”
I think we need to be wary of the ‘static’ part of the word ‘hydrostatic’. It’s actually a highly dynamic equilibrium that maintains a fairly predictable or ‘static’ shape, due to being in the iron grip of gravity. ‘Static’, in this case, doesn’t mean ‘nothing happening’.
tallbloke says, February 4, 2019 at 9:11 am:
tallbloke says, February 4, 2019 at 9:11 am:
No, it’s around 0.12 for The Moon.
Ben Wouters says, February 4, 2019 at 3:53 pm:
Ben, this is not an answer to my question. How would YOU explain the average negative tropospheric temperature profile? How, according to you, is it generated and maintained?
tallbloke says, February 4, 2019 at 5:53 pm:
Exactly. This is what Ben seems not to understand. Why is the constantly overturning lower part of the atmosphere, the part directly, dynamically and constantly interacting (coupled) with the solar-heated surface underneath, the TROPOsphere, where all our weather is, cooling fairly predictably on average with height, while the middle part, lying on top of it, separated from it by the tropoPAUSE, the STRATOsphere, convectionless and stratified, is just as predictably warming with height? What’s the MAIN DIFFERENCE between the two layers? No clue whatsoever …?
@Okulaer,
“No, it’s around 0.12 for The Moon.”
You are right but the devil is in the details. While the Moon’s Albedo may average ~0.12 it matters that the Moon’s Albedo varies with the angle of incidence. Vasavada, Tim Channon and this camel tried three different equations while attempting to model the surface temperature of the Moon see Figure 2 in the link below:
I was hoping to hear your opinion on Plimer. IMHO historians and geologists are much more reliable than the “Climate Science” tribe when it comes to explaining or predicting climate.
Ben Wouters says, February 4, 2019 at 3:43 pm:
Earth’s atmospheric circulation isn’t just driven by convection. It IS convection. Your approach to this issue is along the narrowest path imaginable. What is a Hadley Cell if not a giant convection cell? There are different scales, different orders of magnitude here, different subsystems. A tropical thunderstorm is one such lower-scale subsystem. The thunderstorm and the Hadley Cell have ONE thing in common, though: They both work to transport energy from a place where net heating occurs to a place where net cooling occurs by means of bulk movement of the fluid containing the energy. THAT’S CONVECTION, Ben. That’s what convection does. That’s what convection is. The transfer of heat from one place to another by the movement of fluids.
And what is atmospheric circulation?
“Atmospheric circulation is the large-scale movement of air, and together with ocean circulation is the means by which thermal energy is redistributed on the surface of the Earth.
(…)
The Earth’s weather is a consequence of its [uneven] illumination by the Sun, and the laws of thermodynamics. The atmospheric circulation can be viewed as a heat engine driven by the Sun’s energy, and whose energy sink, ultimately, is the blackness of space. The work produced by that engine causes the motion of the masses of air and in that process, it redistributes the energy absorbed by the Earth’s surface near the tropics to the latitudes nearer the poles, and then to space.”
https://en.wikipedia.org/wiki/Atmospheric_circulation
That’s convective heat transfer, Ben. Please, learn some thermodynamics:
@okulaer,
“What’s the MAIN DIFFERENCE between the two layers? No clue whatsoever …?”
In the stratosphere radiation is the primary heat transfer process. In the troposphere you have radiation, convection and phase changes. The contribution from conduction can usually be ignored (except on airless bodies).
The transition from troposphere to stratosphere is called the tropopause which occurs at a pressure of ~0.1 bar. This has been captured in a set of equations developed from first principles by Robinson and Catling here:
Click to access Robinson2014_0.1bar_Tropopause.pdf
While this paper contains everything you need to replicate the R&C model the software required is IDL which is quite expensive. I have built an Excel spreadsheet that captures the model for Venus, Earth, Jupiter, Saturn, Titan, Uranus and Neptune. I would like to send you a “beta” version of this spreadsheet which is not yet “robust” enough for publishing on Tallbloke. I need all the help I can get!
GC: This sounds like progress!
Ben, in order, my comment length might be a bit much but means I don’t have to comment as often, this stuff easily covers 20-30 pages or more of detail meteorology text:
3:34pm: ”Cooling is due to expansion into the lower pressure higher up.”
A parcel following the general circulation is adiabatic (tradewinds, Hadley cells), a convecting parcel is always diabatic as a convecting parcel is warmer than the ambient surroundings so is always cooling. Just see your own link: “Sunlight hits the ground and heats it. The ground then heats the air at the surface.” by which is meant warmer than ambient and the parcel then convects upwards until the parcel reaches ambient and becomes part of the general circulation.
The height this stoppage happens is determined by the convective available PE (CAPE) which sets the initial max. parcel velocity upwards. This height can be a few feet with almost no CAPE to many thousands of feet with a lot of local CAPE (clouds forming, stormy weather, thunderhead, tornado).
3:40pm: ”Air takes many hours/day to travel that distance. You claim this is a adiabatic process?”
Yes, planetary general circulation occurs at local ambient when you look at tallbloke’s 6:08pm picture, the light blue, medium blue, red circulation of such large air masses is slow as you write equilibrating with ambient at each z. Again, if you are interested “To understand the maintenance of the energy of the general circulation” see sec. 5, p. 165 of the free paper I linked for tall-“I’m too busy with Brexit”bloke 3:09pm.
Convection is different than the general circulation as Ben writes; convection occurs at a different temperature than local ambient so convection is always and everywhere diabatic in a fluid warmed from below in a gravity field. The trade winds are also adiabatic occurring at local ambient.
3:43pm: ”The General Circulation is NOT driven by convection.”
It is in part. Yet again, if you are interested “To understand the maintenance of the energy of the general circulation” see sec. 5, p. 165 of the free paper I linked for tall-“I’m too busy with Brexit”bloke 3:09pm.
3:59pm: ”This site has CAPE data. Most of the world has no potential for any convection worth mentioning.”
Right, mostly hydrostatic atm. in our world. Not sure if that is updated in real time, yes, CAPE units are Joule/kg. If you click on the clear air views, find zero CAPE, mostly hydrostatic, thus any convection stops rising close to the surface and for sure not reaching 100% relative humidity since clouds are NOT forming. Here, on this day and time, tallbloke’s red and blue arrows shown 1:48pm do not exist.
Click on a cloudy area. Get some CAPE and the cloudier the more CAPE. Here tb’s red arrows are at least getting up to 100% RH level, so clouds are forming. But not a huge lot of CAPE since no storms are evident at least when I looked – over hemisphere with Africa and India shown.
tallbloke in response 5:53pm: ” think we need to be wary of the ‘static’ part of the word ‘hydrostatic’. It’s actually a highly dynamic equilibrium”
No need to be wary, hydrostatic means hydrostatic: density is stratified horizontally and zero CAPE. When density is not stratified horizontally, pick up some convective available PE (CAPE) and higher-level convection for your red arrow parcels occurs; non-zero CAPE is hydrodynamic. Go high enough, obtain a cloud but the cloud forming process is not that easy – takes another 20-30 pages of text to cover.
We are trying to take a course in basic meteorology here in sound bites with few if any actually reading the texts/papers/videos. And this has gone on for about ever. I predict won’t stop until everyone takes N&Z advice and actually does the reading required. Which is a pipe dream like “free trade” & that is why tb is so busy.
Ugh, the length…the length! My fingers have blisters.
Continuing, despite the blisters. Kristian asks 8:06pm: ”What’s the MAIN DIFFERENCE between the two layers (troposphere, stratosphere? No clue whatsoever …?”
The troposphere contains a fluid in a gravity field warmed from below up to the tropopause wherein convection can occur. Above the tropopause, the stratosphere is a fluid warmed from above in a gravity field so convection mostly ceases in large regions, density is horizontally stratified, no CAPE.
Locally, yes, large amounts of CAPE (stormy) can drive surface parcels so high that cloud tops cauliflower out into the stratosphere irritating airplane pilots who then ask ATC for another (smoother) flight level. By and large though, stratosphere has no convecting weather of its own though it can form clouds.
Kristian incorrectly writes: ”Earth’s atmospheric circulation isn’t just driven by convection. It IS convection.”
Read & understand what Ben wrote, they are two different processes, Kristian, heck they each even have their own wiki page! Tradewinds (all winds) are also driven by pressure differences and they are mostly horizontal where convection is always upward for short and long distances depending on convective available PE (CAPE) & only tropospheric. You also need to read the Lorenz paper I linked for tb 3:09pm to understand the maintenance of the energy of the general circulation.
@Tallbloke,
“GC: This sounds like progress!”
I will send you my R&C spreadsheet. It has problems similar to the lunar model spreadsheet I sent you. At times like this I really miss Tim Channon. I am hoping to find people who can compensate for my shortcomings as Tim did.
I am reaching out to ex-colleagues in the Duke university physics department and people on your blog. I don’t want to embarrass anyone by naming names.
tallbloke says: February 4, 2019 at 5:53 pm
For convection to reach higher up, it MUST reach the condensation level and start “burning” latent heat. Dry convection dies out pretty soon.
The force acting against gravity is pressure, and pressure reduces very predictably with altitude.
The dynamics come from changing temperature/density within this gravity/pressure base situation.
Almost the entire atmosphere is in HE. Known exceptions are tornadoes and hurricanes.
okulaer says: February 4, 2019 at 8:56 pm
Shows you and the person in the linked video have no clue how our atmosphere actually works.
Find a good text on basic meteorology.
Trick says: February 4, 2019 at 11:07 pm
Did read your comment and we seem to be mostly on the same page.
Travelling today and no time. Hope to pick up this discussion soon (Wifi access allowing 😉
Trick says, February 4, 2019 at 11:57 pm:
Blah-blah-blah.
No. This is pure semantics on your (and Ben’s) part. The principal thermodynamic definition of “convection” is – like I pointed out – a mode of heat transfer specifically seen in fluids (gases and liquids) whereby the energy is transferred from one place to another through the movement of the fluid itself. And that is precisely what the atmospheric circulation is and does. On a LARGE SCALE. And then you have convectional cells on much smaller scales as well … The one doesn’t exclude the other.
This ossified insistence on the “convection-is-only-ever-upward” mantra is so narrow, so limiting, that it only hampers the progress of the larger – and much more interesting – discussion. Stop it and move on …!
If it’s SUCH a big problem defining the atmospheric circulation as a large-scale convective system (the surface of the Earth is heated by the Sun, setting the air above in motion as a result), then just call it “atmospheric circulation”. Fine. We’re still talking about the same basic phenomenon.
Ben Wouters says, February 5, 2019 at 5:45 am:
Yawn. It shows you have no grasp of thermodynamics. Read about convective heat transfer.
Atmospheric convective circulation moves more energy towards the poles than the oceans do. And considering how much lower the equator-pole temperature gradient is on planets with atmospheres than on airless bodies (on Venus with its extra massive atmosphere the gradient is almost zero), that’s a lot of energy. And before anyone gets sassy with saying it’s horizontal advection that’s moving the energy, consider that surface winds on Venus are very, very slow.
So all this “there’s a bit of cape near the equator but hardly anything anywhere else” nonsense is just, well, nonsense. Yes, it’s the big engine driving the system (as I said three days ago), but that solar energy driven engine shoves the high altitude air latitudinally a long way until it sinks again at the horse latitudes (Hadley-Ferrell cell boundary).
Trick: for your cheek, here’s your detention homework.
Click to access PLAN-A-FINAL.pdf
🙂
TB: pdf – link problem?
oldbrew, my guess is tb was trying to point to a brexit plan he needs me to read.
—-
Kristian 5:52am writes incorrectly again: ”This is pure semantics on your (and Ben’s) part.”
Commenters are discussing buoyant convection when discussing parcels and convective available PE (CAPE from tallbloke’s 1:48pm red buoyant convection arrows). A Hadley cell (tb 6:08pm) is mechanical convection (from pressure gradients, see Lorenz paper to understand its maintenance). Buoyant convective parcels (diabatic not at ambient) are different than the planet’s forced general circulation (at ambient).
Moreover, one can find a host of ambiguous and confusing terms in comments. If Kristian wants to correctly discuss meteorology without leading to befuddlement, then Kristian will use the generally accepted lingo of those in the business & point to that generally found in published texts/papers on the subject when any commenter goes astray:
http://glossary.ametsoc.org/wiki/Convection
Ben 5:45am: ”Shows you and the person in the linked video have no clue how our atmosphere actually works.”
The bio/resume of the person in Kristian’s video link shows he likely has some clues but has not passed a college course of study in basic meteorology. Personally, I would not rely on that particular video for meteorological information, prefer to rely on actual pro meteorologists and their society like EN Lorenz.
“I’m taking no notice of these upstart Calvinists and will be following the doctrine of the Holy Roman Church. How dare they interpret the bible without submitting instead to the dogma of his holiness?”
Trick says, February 5, 2019 at 2:36 pm:
*Sigh*
Commenters are also discussing atmospheric circulation and the tropospheric temperature profile as if they didn’t have ANY relation whatsoever to convection. That, to me, is simply too far out … We need to get real (that is, join practical reality) about this issue before we can make ANY progress whatsoever. The thing that can only move upward in a gravity field is “buoyancy”, not convection. (Note: Convection, the thermodynamic phenomenon, not the term itself.) Yes, there is terminology out there to distinguish between the bulk air movement of different subsections of those giant convection cells of Earth’s troposphere, like advection/wind, orographic wind, thermal wind, front, ascending limb, descending limb, and I am of course fully aware of the meteorological definition of convection in all this. The point I’m making is simply that you need to look beyond those narrow theoretical definitions and try to see the larger picture, beyond the tip of your nose, that is, the physical concept of convection – heat transfer through bulk mass movement in a fluid. All those fancy terms above describe distinct parts of the same convective system, ultimately driven by surface heating/evaporation and resulting buoyancy. I mean, why try to make such a simple matter into such a complicated and convoluted one when it doesn’t have to be at all …!?
https://en.wikipedia.org/wiki/Convective_heat_transfer
https://en.wikipedia.org/wiki/Convection#Atmospheric_circulation
https://www.ck12.org/earth-science/circulation/lesson/Circulation-in-the-Atmosphere-HS-ES/
https://www.e-education.psu.edu/earth111/node/752
tallbloke 5:30pm: “God does not play dice.”
The thermal conductivity of air in the troposphere is independent of atm. pressure although it does decrease with decreasing temperature. Evaporation depends on the state of the liquid not the state of the air above the liquid so evaporation is also independent of atm. pressure at planetary surfaces.
Kristian asks: “why try to make such a simple matter into such a complicated and convoluted one when it doesn’t have to be at all …!?”
Convoluted? No. Complicated yes, because the topic of discussion, a planetary atm., is complicated. The interesting discussion is about different atm. science principles supporting tallbloke’s red/blue arrows in pictorials at 1:48pm and 6:08pm. Using your links, you ought to be able to understand the differences; they are not semantic differences.
Trick: “Evaporation depends on the state of the liquid not the state of the air above the liquid so evaporation is also independent of atm. pressure at planetary surfaces.”
No it isn’t. Let me refer you back to my comment here:
Viz:
Click to access 2060.pdf
This experiment found that 25ml in a 250ml beaker of water at 20C evaporated in ~150 minutes when air pressure was reduced to ~2.86 Torr (381.2952Pa). This is ~266 times lower than Earth’s surface air pressure.
I don’t have a 250ml beaker to hand or the controlled conditions to maintain it at 20C, but I think we all know that it would take days rather than 2.5 hours for the water to evaporate at sea level pressure in the same fairly still conditions (say, out of a cup in our home with central heating running at 20C).
Water evaporating takes quite a lot of heat away — 540 calories per gram — when it evaporates.
https://van.physics.illinois.edu/qa/listing.php?id=1440&t=water-evaporation-rate
So, I think we can conclude that air pressure suppresses the rate of evaporation, and that this means the ocean surface has to rise to a higher temperature in order to lose heat as fast as it gains it from the Sun.
This is one of the ways pressure increases Earth’s surface temperature. Not by “pressure creating heat”, but by reducing the rate at which heat is lost from surface to atmosphere, thus forcing the surface temperature to rise until it can evaporate water fast enough be in equilibrium with the overlying atmosphere.
Let me remind tb, refer back to my 3:29pm: What happened to the state of the test beaker liquid? Fig. C shows the state of the liquid changed hugely, rapidly thus so did evaporation. Test Fig. C confirms what I wrote, evaporation depends on the state of the liquid.
Fig C doesn’t show anything of the sort. Fig C shows the liquid stayed in the liquid state for the duration of the experiment.
Yes, the water stayed liquid phase so evaporating. Look at the dotted line for “water only”, temperature declines from 20-25C to about 0C in the time of a few minutes then recovers to about 7-8C and evaporation complete at about 3 hours. The evaporation rate at 20C & ~8C was higher than ~0C.
Evaporation from the liquid phase is a random process, purely by chance some lucky water molecules acquire sufficient KE to escape which depends on the state of the liquid. The higher the temperature state of the liquid phase, the greater the number of molecules with sufficiently high KEs to escape, hence the greater evaporation rate. Air/water vapor pressure above the liquid is immaterial to that escape process, only the temperature of the liquid matters for evaporation rate as in this test.
Lol.
The high initial rate of evaporation reduces the temperature of the water and slows the evaporation rate. Nonetheless, the water remains in the liquid state and evaporation is complete in under three hours at the very low air pressure.
At Earth’s sea level pressure, the evaporation would have taken days, not hours at 20C.
Yet Trick believes the very low pressure had nothing to do with the accelerated evaporation rate of 25ml of water, containing many millions of molecules of H2O.
You can trick some of the people some of the time.
You can lead a horse to water, but you can’t make him drink the Koolaid. 😉
”Yet Trick believes the very low pressure had nothing to do with the accelerated evaporation rate of 25ml of water, containing many millions of molecules of H2O.”
Nothing? That is what tb writes, to me the test shows the state of the liquid water temperature changed from 20-25C to ~0C and back to about ~8C, so that’s something.
Determined to miss the point eh Trick? Ah well. Never mind.
As I understand the point, you are trying to make the case with this test that atm. pressure affects the evaporation rate. You can’t make that case with this test. Pressure affects the liquid water temperature state in the test; the liquid water temperature state determines its evaporation rate.
Lol
tb enjoys a good laugh at the expense of enjoying further discussing the process. The temperature of the “water only” in Fig. C rapidly decreases as the vacuum is applied. tb should instead discuss why is that instead of laughing.
The evaporation of the water slowed as its temperature state decreased but under nil pressure another process takes over.
Too bad they don’t have a video of the process. What should be shown is the water initially forming internal bubbles & rapidly boiling away its internal KE into the vacuum first few minutes and maybe some water ice forming. They developed the test maybe they avoided much ice forming point so as not to worry about sublimation time too. As the sample of liquid “water only” decreases towards “evaporation complete”, I’d guess the beaker temperature drives the thinning water a bit warmer as shown and rapid surface evaporation does increase from the low T point.
After all this is what tb’s test link is discussing: …the natural state of water in the surface conditions of airless bodies is either in the form of ice or vapor that escapes in low gravity environments.
tallbloke, I’m trying to post a comment, but it won’t get through. Am I doing something wrong?
Okulaer, It’s not showing up in moderation or the bit bucket. Does it have more than 8 links in it? Try breaking it into several comments if so.
Trick, we can test your hypothesis that it’s the temperature that matters and not the pressure by putting our cup containing 25ml of water under 1 bar of Earth’s standard sea level pressure into the freezer until it’s near 0C, and then bringing it back out into our 20C centrally heated home kitchen. It’ll still take days to evaporate rather than the <3hrs it took under the reduced pressure in this experiment. https://www.hou.usra.edu/meetings/lpsc2014/pdf/2060.pdf
Please stop obfuscating what is a very simple observation: Increased pressure impedes (reduces the rate of) evaporation.
I agree that reducing temperature will also reduce evaporation rate. But that didn't prevent this water sample in a vacuum chamber completely evaporating many times faster than it would at normal atmospheric pressure.
tallbloke, this discussion ought to add to your knowledge and focus your thinking to understand why an aspect of N&Z’s 2017 paper is flawed as it violates 1LOT as Dr. Spencer and Willis (probably others) have pointed out.
If your water sample in the freezer follows the same temperature profile as the water sample in your link to 2060.pdf, then the two samples evaporation rate will be exactly the same over the test as evaporation rate depends only on the temperature state of the liquid water. So why is there a difference in time to complete evaporation?
In your 2060.pdf test, the pressure is reduced to nil causing a large amount of the water to boil away and be eliminated in first few minutes and likely freeze in some portions. Here, I found a short video for you of such a process:
https://sciencedemonstrations.fas.harvard.edu/presentations/boilingfreezing-water-vacuum
N&Z 2017 p. 17, 14: “Furthermore, the relative atmospheric thermal enhancement (RATE) defined as a ratio of the planet’s actual global surface temperature to the temperature it would have had in the absence of atmosphere is fully explicable by the surface air pressure alone (Eq. 10a and Figure 4)….. adiabatically boosts the kinetic energy of the lower troposphere beyond the level of solar input through gas compression.”
Note both your freezer and the vacuum pump are plugged in to a source of energy satisfying 1LOT. This source of energy N&Z 2017 miss in a planetary atm. in a way that is obvious to many but not all. In fact, your powered freezer uses the powered low-pressure process in the video to cool the liquid water sample below ambient.
Trick says, February 5, 2019 at 8:31 pm:
“Convoluted? No. Complicated yes, because the topic of discussion, a planetary atm., is complicated. The interesting discussion is about different atm. science principles supporting tallbloke’s red/blue arrows in pictorials at 1:48pm and 6:08pm. Using your links, you ought to be able to understand the differences; they are not semantic differences.”
Trick, get over yourself.
K.e.r.r.y A. E.m.a.n.u.e.l, in his 1994 textbook on the subject, “Atmospheric Convection”, neatly articulated the point I’ve been trying to make here all along, that the concept of “convection” has both a more fundamental (‘thermodynamic’) definition and at the same time a much more narrow or restricted (‘meteorological’) definition, and that these two definitions are not in any way mutually exclusive; “convection” can be – and IS – both things:
https://tinyurl.com/yddmzh4a
Okulaer, your comments finally showed up in the spam bin. I approved the longest one and removed the other three. It’s probably a wordpress spam filtering thing due to you using two accounts to post the same material.
Thanks, tb.
–So, I think we can conclude that air pressure suppresses the rate of evaporation, and that this means the ocean surface has to rise to a higher temperature in order to lose heat as fast as it gains it from the Sun.–
So if Earth had Mars gravity – about 1/3rd Earth gravity, then Earth ocean would have lower average temperature.
And since Earth average surface temperature is about 17 C, it would lower than this?
And since Earth tropical average surface temperature is about 26 C, would it mostly be about lower this temperature, rather than ocean surface temperature outside the tropics which averages about 11 C ?
Or would it not be about average temperatures and instead be mostly be about lowering the presently highest surface ocean temperature which presently gets as high as about 35 C?
–This is one of the ways pressure increases Earth’s surface temperature. Not by “pressure creating heat”, but by reducing the rate at which heat is lost from surface to atmosphere, thus forcing the surface temperature to rise until it can evaporate water fast enough be in equilibrium with the overlying atmosphere.–
It seems to me that if Ocean evaporates more at lower temperature, that might cause Earth to have a higher average temperature.
And I am not talking about increasing greenhouse gases. Rather I mean it allows oceans to be cooler yet warm the rest of world, more.
And since I more interested in Mars.
And Mars has about 1/3 Earth gravity.
If covered Mars tropics with shallow ocean.
10 meter deep, and adding water so it is always 10 meters deep.
And adding heat so surface is always 5 C. So adding to heat in addition to the heat added by sunlight.
Does having the tropical ocean surface at 5 C, cause more or less global warming as compared to having 1 gee of gravity?
Apologies, very limited time and a steam driven Wifi connection.
Hadley circulation (and sea breezes in a limited fashion) follow this basic mechanism:
– uneven heating of the surface by the sun resulting in a temperature gradient from equator to poles.
– overlying atmosphere in HE is expanded (see 500 mb and 200 mb (or 250 or 300) height charts showing the altitude of the pressure plane in decameters.
– due to the higher pressure at the SAME ALTITUDE near the equator than towards the poles at eg 5, 10 or more kilometers up air flows towards the poles.
– due earths rotation the Coriolis effect turns these flows eastbound and the air accumulates around 30 N/S forming the Subtropical jetstream.
– air leaving the Equator at altitude creates a surface low pressure
– air accumulating around 30 N/S creates a surface high pressure
– between these high and low pressure areas surface winds flow, again turned by the Coriolis effect, this time westbound and forming the Trade winds.
– near 30 N/S air sinks replacing the air leaving at the surface
– Near the equator air rises replacing the air that leaves at altitude, closing the Hadley circulation.
Please explain how this mechanism can be the same as a convective flow in a pan filled with a liquid heated from below.
Ben W: – near 30 N/S air sinks replacing the air leaving at the surface
Paging Trick. Have you got that now?
Ben Wouters says, February 8, 2019 at 1:07 pm:
*Sigh* Like this: “All motions that can be attributed to the action of a steady gravitational field upon variations of density in a fluid may be called convective motions and thus almost all the kinetic energy of the earth’s atmosphere and oceans and the bulk of that of the many fluid systems in the known universe results from convection; other fluid motions are attributable to tidal and electrodynamic forces.”
Two thoughts in your head at the same time, Ben. Try it. “Convection” can be both the wider definition AND your narrow definition.
Does ths sub-argument signify agreement that convection and LH WV transport dominate over the radiative? If so, that must be progress indeed. Because gases by definition are a phase of matter that will not stay down when thermalised in an atmosphere. As nature demonstrates, do we all agree then?…..Brett
Brett, we can see they dominate because according to NASA’s energy budget, they shift twice as much net heat off the surface as LW radiation does. If radiation was dominating, we’d see a lot less convection. As it is, the mean free path for radiation and the frequency of collisions thermailising O2 and N2 in the dense lower troposphere makes radiation a pretty inefficient way to move energy up the column. Of course, the downward radiation Roy Spencer believes warms the surface is soon re-absorbed or converted to sensible heat just below the cloud base and convects upwards…
Handy video on atmospheric convection
https://www.e-education.psu.edu/earth111/node/752
See also: The Orographic Effect
https://www.e-education.psu.edu/earth111/node/751
Good little video that OB. Well worth watching.
tallbloke says: February 9, 2019 at 9:27 pm
Seriously??
– why is the air moving from Eq. to 30 N/S in the first place
– why are the Trade winds and westerlies influenced by the Coriolis effect and is the upper flow depicted as moving straight from Eq. to 30 N/S
-why does the air sink around 30 N/S and not eg around 5 N/S or 60 N/S
– what happened to the SubTropical jetstream
etc. etc.
okulaer says: February 8, 2019 at 6:05 pm
Yes, just as a Formula 1 racing car and a bicycle are both vehicles, I do hope even you will understand they are not comparable at all.
Read your own text:
So in atmospheric sciences one generally uses the more restricted definition of convection, and since we are discussing atmospheres…..
The distinction between “convective” (= buoyancy driven, like thermals, thunderstorms and even tornadoes) and “nonconvective” (= driven by differential heating in the horizontal, like Hadley circulations and sea breezes) is rendered less academic…….
Ben W, instead of criticising how little can be included in a 2 minute video, why don’t you build on it instead of carping about it?
– why is the air moving from Eq. to 30 N/S in the first place?
Because air flows from higher pressure to lower pressure.
– why are the Trade winds and westerlies influenced by the Coriolis effect and is the upper flow depicted as moving straight from Eq. to 30 N/S?
Because schematics are limited in their scope, and less dense air is less affected by coriolis.
-why does the air sink around 30 N/S and not eg around 5 N/S or 60 N/S?
Because that’s what the pressure which sets the slope of the equator-pole gradient and the solar input determines.
– what happened to the SubTropical jetstream?
Nothing, it’s just not essential to include it to make the points the video demonstrates
In an ironic twist of irony, we’re actually in agreement with Willis on this aspect. The tropics convect a LOT, and this drives the circulation.
tallbloke says: February 10, 2019 at 9:46 am
I gave a basic explanation of the Hadley circulation here:
I left out some details like the Tradewinds inversion or the actual mechanism that makes the air accumulate around 30 N/S
Iso commenting on this I see again a nonsensical depiction of the Hadley circulation being presented as something useful.
If you want to keep believing that the Hadley Circulation is driven by thunderstorms near the equator then say so. Doesn’t change the fact that this idea is nonsense.
tallbloke says: February 10, 2019 at 12:33 pm
Do you mean that in the tropics a lot of thunderstorms develop and that they drive the Hadley circulation?
— – why is the air moving from Eq. to 30 N/S in the first place?
Because air flows from higher pressure to lower pressure. —
I would say it is related to bouyancy, weight/density.
Lighter air, rises and denser air, falls.
As general rule, water is always evaporating, though water can have net gain from condensation.
Or even when water condenses at the same time it is evaporating.
In a cloud water is both evaporating and condensing.
A wet lapse rate is a process of evaporation and condensation within the air.
The tropics has a higher average temperature. Tropics is on average, evaporating more water.
One can call the addition of H2O gas, pressure, so in that sense, air flows from the higher partial pressure of water vapor.
Getting back to my fav topic, tropical ocean on Mars.
Small amounts of liquid water on Mars will evaporate quickly. Large amount of water would evaporate less per square meter area. Though, millions of square meters evaporates lots of water.
But I want remain focused on amount water evaporating per square meter.
Water on Mars both evaporates and condenses. At equator the water evaporating will have larger percent of it condensing before it can leave the tropics. Likewise any water evaporating near 25 degree latitude will have will have a lower percentage of it condensing before leaving the tropics.
To conserve water, one could have higher temperature water at equator, as compared ocean surface temperature nearer to edge of tropics (25 degrees North and South).
And despite higher water temperature at equator, one could lose, less water per square meter as compared to water lost per square meter at cooler water near 25 degrees latitude.
Ben Wouters says, February 10, 2019 at 8:03 pm:
You are a strange fellow, Ben. [Snip]
[Moderation note] Snipped for courtesy.
Ben W: If you want to keep believing that the Hadley Circulation is driven by thunderstorms near the equator then say so. Doesn’t change the fact that this idea is nonsense.
Not just thunderstorms. The tropics are where Earth gets most solar input. It’s not just humid air that’s buoyant. Warmed air is too. It rises. That displaces other air sideways and downwards. The surface area of the tropics is big compared to the extra-tropics in each hemisphere. Think about it.
tallbloke says: February 11, 2019 at 1:43 pm
Depends entirely on the temperature profile of the overlying atmosphere. If this profile is absolutely stable warm and/or humid air does NOT rise.
Over the desert belts around 30 N/S the air actually sinks. (surface high pressure subsidence)
How do you explain this? Deserts are hot afaik.
Re — Ben Wouters says: February 13, 2019 at 5:53 am
‘Warm moist air’ rising from the equator between the two ‘cool dry’ descending around 30 N/S…
I have still not seen any convincing explanation why albedo can be ignored in the N&Z discovery.
Two otherwise identical rock planets with identical atmospheres, one covered with a thin layer of limestone, the other with coal, will have different albedos, but will have same temperature according to N&Z. Why?
Again – albedo can’t cause itself.
oldbrew says:
February 13, 2019 at 3:34 pm
Again – albedo can’t cause itself.
Albedo will be different with two different surfaces; black rough coal and white smooth limestone.
oldbrew says: February 13, 2019 at 10:35 am
30N and 30S are 3600 nm (~6667 km) apart. Are you now saying that buoyancy works at these distances??
If rising buoyant air near the Eq. reaches its neutral altitude it stops rising and just sits there.
– What makes it move towards the poles?
– Why does it accelerate while moving pole ward?
– Why does it create the Tradeiwnd inversion on its way poleward?
– Why does the air form the Subtropical jet?
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter10/jet_streams.html
Ben W – see here: Horse latitudes (2 – formation, 3 – migration)
https://en.wikipedia.org/wiki/Horse_latitudes
oldbrew says: February 14, 2019 at 9:37 am
I’m aware of all this, but no answer to the 4 simple questions I put forward.
The image you provided is nonsense, since the pressure gradient force at altitude is from equator to poles, so air is not flowing against this gradient as shown in the Ferrel Cel.
Ferrel cell explained here…
The circulation within the Ferrel cell is complicated by a return flow of air at high altitudes towards the tropics, where it joins sinking air from the Hadley cell.
https://www.metoffice.gov.uk/learning/atmosphere/global-circulation-patterns
Met office and Wiki’s explanations are clear but simplified. I am supposing its what happens, but at an Earth axial tilt of 23.xx degrees. That should complicate things. Then throw in a bigger spanner, an earth tilt of about 14.5 degrees. What would really happen in polar regions?
oldmanK says: February 15, 2019 at 8:03 am
Not simplified, they lack the most essential part of al these phenomena:
what drives the overall flow from equator to poles at high altitude (around tropopause level) and creates the two distinct bands of jet streams: Subtropical jet and Polar jet.
The surface winds are a consequence of all that happens at altitude.
“Pressure decreases less rapidly with height in warmer air than in cooler air.
There is a temperature gradient from the equator to the poles.
So, at high altitudes there is a pressure gradient from the equator to the poles (and therefore) strong winds at high altitudes.”
Pablo says: February 15, 2019 at 5:35 pm
One would hope this to be basic knowledge for anyone discussing climate and/or weather at anything above kindergarten level.
Yet Hydrostatic Equilibrium is apparently unknown to most taken part in the discussions on this site.
Ned, the Poisson Formula/Relation, referred to by Maxwell when he demolished radiatve atmospheric theories in favour of the Gas Laws, pp330-350 of ‘Theory of Heat’, etc., if I understand things right, is T/Tc = (P/Pc) to the Power of R/Cp or 0.286 in Earth’s atmosphere.
I tend to take James Clerk Maxwell seriously especially compared to Willis, who ignores him. Which might have amused JCM.
I work on the understanding that Pressure describes gaseous internal KE, with T measuring an effect ie energy transfer to a measuring device.
Meanwhile we have Leif Svaalgard and friends ignoring the effects of the Gas Laws in atmospheres under irradiation. But the Starmen’s formation model uses those Gas Laws for all initial heating from c.2K to ignition. With some help from Quantum Tunnelling and Statistical Mechanics to jump a final hurdle, as I understand it. All that seems sensible to me, as far as Quantum can be. Leif, Leif, paging Leif! Your stars cannot radiate until random walks get their photons to the convective zone where atoms reform and Ideal Gas Laws operate. Comments please, and well Ned I know this is about Dimensional Analysis, another Maxwell idea more or less, but your take would be educational for me at least…..Brett
Pablo: So, at high altitudes there is a pressure gradient from the equator to the poles (and therefore) strong winds at high altitudes.”
And yet atmospheric angular momentum keeps the jetstreams moving more zonally than meridionally, although they get a bit loopy when the Sun goes weak.
Petter Tuvnes: I have still not seen any convincing explanation why albedo can be ignored in the N&Z discovery.
Two otherwise identical rock planets with identical atmospheres, one covered with a thin layer of limestone, the other with coal, will have different albedos, but will have same temperature according to N&Z. Why?
Read the first N&Z paper again.
Ben W: Over the desert belts around 30 N/S the air actually sinks. (surface high pressure subsidence). How do you explain this? Deserts are hot afaik.
The reason why they are deserts in the first place s because the descending air is dry, and heated by adiabatic compression. Back at surface it gets even hotter during the day, heated further by the sun baked surface, and rises. But it also gets cooled during the night, because the desert surface loses heat quickly after sunset.
re. horse latitudes…
In Hadley’s original explanation, the winds continued all the way to the pole, and then sank to return all the way to the equator (like a global sea breeze). Hadley was not aware of the law of conservation of angular momentum and thought the poleward moving air would conserve its east-west velocity. But because the poleward moving air is getting closer to the axis of the rotating Earth, it spins up continuously until it reaches maximum in the midlatitudes. This is where the fast moving air breaks down into large eddies (or turbulence, see below). The breakdown of the flow is also accompanied by a sinking motion towards the surface just south of the jet stream axis. This subsidence is the reason for the horse latitudes. When it reaches the surface, the air spreads equatorward and poleward. The equatorward spreading air acquires a westward movement due to Coriolis and the trade winds are formed. It continues to move westward and equatorward, gathering moisture, and converging at the Intertropical Convergence Zone.
tallbloke says: February 16, 2019 at 8:16 am
Coriolis effect perhaps?
Jetstreams move parallel to the pressure gradient when the pressure gradient force and the Coriolis effect balance out. On Earth this happens around 30 N/S and 60 N/S roughly and changes according the seasons and differential heating over continents and oceans.
tallbloke says: February 16, 2019 at 8:25 am
Again, air will only rise if the temperature profile of the overlying air allows it to rise.
Dry air over a desert will not condense while rising and stop rising pretty soon since it cools at the DALR.
@Petter Tuvnes,
“I have still not seen any convincing explanation why albedo can be ignored in the N&Z discovery.
Two otherwise identical rock planets with identical atmospheres, one covered with a thin layer of limestone, the other with coal, will have different albedos, but will have same temperature according to N&Z. Why?”
In my opinion Albedo and the composition of gases in a planet’s atmosphere should have some effect yet the experimental evidence is lacking. Nikolov & Zeller tell us that there are two primary variables that determine the surface temperature of rocky planets, specifically pressure and TSI (Total Solar Irradiance).
For example, numerous comments upthread show that the temperature difference between Venus and Earth over a wide range of pressures (up to one bar) can be explained in terms of TSI alone. The TSI ratio is 1.911 so according to Stefan-Boltzmann the temperature ratio should be (1.911)^0.25 = 1.176 and that corresponds closely with observations.
I agree with “okulaer” who says this is a crazy result given that Stefan-Boltzmann applies to black bodies which neither of these planets are. Earth has a Bond Albedo of ~0.31 compared to ~0.76 for Venus.
“Oldbrew” keeps making cryptic comments such as “Albedo can’t cause itself” but he refuses to explain what that is supposed to mean. My patience with “Oldbrew” is wearing thin so I hope he will come down from his mountain top and share some of his wisdom with us little people.
–In my opinion Albedo and the composition of gases in a planet’s atmosphere should have some effect yet the experimental evidence is lacking. Nikolov & Zeller tell us that there are two primary variables that determine the surface temperature of rocky planets, specifically pressure and TSI (Total Solar Irradiance).–
I think Albedo effects how much sunlight is absorbed.
But there are number of things which affect how much sunlight is absorbed.
And Moon is black as coal and the Moon absorbs very little sunlight. It not clear to me how one could make body absorb as little sunlight as moon does. The only thing that comes to mind is if the Moon had a slower rotation. Since Mercury does have slower rotation if might absorb less of the sunlight. Of course it’s closer to the sun and gets more sunlight, I saying it absorbs a small fraction of the energy of the sunlight.
gbaikie says: February 17, 2019 at 6:47 am
Imo Albedo is just a number that indicates what percentage of incoming solar radiation is REFLECTED, and thus has no effect on the temperature of a planet.
The moon absorbs ~90% of incoming solar, Earth ~70%.
The difference between the two is the composition of the surface.
Lunar regolith warms up very fast, but only max.~ 50 cm deep. So lunar surface temperatures are close to radiative balance temperatures on the sunny side (with some lag). The dark side is much hotter than radiative balance (~80K iso ~0K)
On Earth the oceans absorb solar in the first 5-10m and by mixing this energy is transferred to max. ~500m deep. So temperatures are nowhere near radiative balance temperatures.
The reason Earth is so much warmer than the moon is the base temperature of the crust and oceans of around 275K (on average) caused by the hot interior of the Earth. This heat is “trapped” by the solar heated warmer surface layer (~10m for continents and ~500m for oceans)
Re albedo: what is a climate forcing and what is a response to the forcing? Albedo is currently proposed as both.
Venus is much hotter than Earth but also has a much higher albedo.
The bond albedo of Venus is 0.75.
https://www.universetoday.com/36833/albedo-of-venus/
Jupiter with an albedo of 0.52 still has a super-hot interior.
On Jupiter it seems that the jet streams are driven by the planets’ own heat, which are the result of its intense atmospheric pressure and gravity.
https://www.universetoday.com/15097/temperature-of-jupiter/
The reason the oceans are an average temperature of 4ºC or 277ºK is that anything colder is less dense and floats to the surface to be warmed by the sun. Heat flow from the core is too small to heat the total mass of the oceans apart from localised tectonic events. The sea floor with its thinner crust acts as a very effective insulator as does the atmospheric temperature/pressure gradient above to keep surface waters at an average balmy 17C.
Pablo says: February 17, 2019 at 10:25 am
The only water that sinks to the ocean floor is AntArctic Bottom Water (AABW)
https://en.wikipedia.org/wiki/Antarctic_bottom_water
Continental crust is thicker and thus a better insulator. The flux is much lower than through oceanic crust (~65 mW/m^2 vs ~101 mW/m^2)
Yet the temperature at eg 3 km deep is from ~350K to ~550K.
Reason is exactly the same as for the oceans:
the solar heated surface layer almost completely blocks Earths heat from escaping to the atmosphere and space.
The atmosphere is NOT a very effective insulator. Earths surface at ~290K without atmosphere would radiate ~400 W/m^2 to space. The atmosphere reduces this to ~240 W/m^2.
So my question is:
why are the deep oceans ~275K, ~80K above the average Lunar temperature?
BW:
Insulating as in preventing heat loss from the ocean downwards, thus preserving the 4ºC temperature of water in its most dense form. One of many unusual properties of water in all its forms that make Earth unique.
@gbaikie,
“The only thing that comes to mind is if the Moon had a slower rotation. Since Mercury does have slower rotation if might absorb less of the sunlight.”
I am reasonably confident in my calculations for the lunar surface temperature. For airless bodies such as the Moon and Mercury it is easy to show that even a tiny change in Albedo has a dramatic effect on surface temperature.
For example in the case of our Moon, Albedo is a function of the angle of incidence. At noon the Albedo is 0.89 but only 0.39 at dawn or dusk. This is not a small effect. On the equator failure to take this into account will cause errors of 75 Kelvin in surface temperature at dusk and up to 100 Kelvin within the first hour after sunrise.
In the case of Albedo a lunar model can be checked against the Diviner LRE measurements. No such direct experimental data is available for checking models that include rotation rate. Nevertheless I contend that reducing the Moon’s rate of rotation will reduce the average temperature. Ned Nikolov does not agree so what do you think?
BW:
Still air is a very good insulator if as warm or warmer than than a surface. The average temperature of air is what determines the average temperature of earth’s near-surface crust.
Given that this post mentions Dr. Roy Spenser here is a link that includes his model of lunar temperature:
http://www.drroyspencer.com/wp-content/uploads/simple-radiative-EBM-of-sfc-and-NOatm-with-diurnal-cycle.xlsx
This spreadsheet uses a single constant to describe Albedo so when you enter 0.11 into the Absorbance field (Absorbance = 1 – Albedo) you will find the temperature errors relative to the Diviner LRE data mentioned in my last comment.
Modifying Dr. Roy’s spreadsheet to include Vasavada’s model for lunar Albedo reduces the model vs. data errors to less than 3 Kelvin for the entire lunar day.
Pablo says: February 17, 2019 at 3:01 pm
The ocean floor actually warms the ocean water in contact with it (~100 mW/m^2)
Without cooling at high latitudes the geothermal flux would warm the oceans 1K every ~5000 year.
Entire Ocean Heat Content is provided by the 100 mW/m^2 flux every ~1,5 million year.
Pablo says: February 17, 2019 at 3:15 pm
Are you saying that the air warms the surface and the crust near the surface??
In real life it is the other way around. Sun wamrs the surface, surface warms the air above it.
See eg. the Nocturnal Inversion for a neat demonstration of this basic fact.
@oldbrew,
That link on Jupiter was interesting but it posed more questions than it answered. In their 2012 & 2014 papers, Robinson & Catling model seven worlds in our solar system and three of them have significant internal heat sources.
The heat sources are described by a single number. For example Jupiter has 5.40 Watts/m^2. This approach treats the internal source as if it was an external source. Saturn has 2.01 W/m^2 and Neptune only 0.43 W/m^2.
So what can be generating such huger amounts of heat? Chemical reactions are not adequate so we are left with nuclear reactions. Given the relatively small size of Jupiter you can rule out hydrogen fusion and CNO reactions. My guess is that you have large scale fission of Uranium occurring inside Jupiter.
Before you start laughing remember that respected scientists such as Kuroda have suggested that natural nuclear reactors exist on Earth:
https://gizmodo.com/there-s-a-naturally-occurring-nuclear-fission-reactor-i-1475445638
BW says:
“Are you saying that the air warms the surface and the crust near the surface??
In real life it is the other way around. Sun warms the surface, surface warms the air above it.
See eg. the Nocturnal Inversion for a neat demonstration of this basic fact.
No, just that it insulates it.
See:
http://www.halesowenweather.co.uk/soil_temperatures.htm
A nocturnal inversion at the surface is simply a radiative returning of a well mixed daytime boundary layer dry lapse rate to a moist lapse rate with its increase of PT with height.
The dry lapse/gravitational lapse rate of 9.8ºC/km with no increase of PT with height occurs in well mixed air regardless of moisture content.
BW says:
” The ocean floor actually warms the ocean water in contact with it (~100 mW/m^2)
Without cooling at high latitudes the geothermal flux would warm the oceans 1K every ~5000 year.
Entire Ocean Heat Content is provided by the 100 mW/m^2 flux every ~1,5 million year.”
Exactly… not so much warming, but a very good insulator.
Pablo says, February 17, 2019 at 5:02 pm:
Pablo, I’ve tried reasoning with this person on several occasions, using this exact same explanation of what’s really going on. But he’s just not willing to see it. His head is stuck so deep into the ground, there simply is no talking to him. Whenever I enter into an argument with this guy, I end up feeling like Matt Dillahunty in the video below, trying his best to spoon-feed reality to an indoctrinated Christian nitwit:
Ultimately, all you can do when faced with this kind of self-imposed ignorant obstinacy, is throw your hands up in disbelief. And move on.
gbaikie says, February 17, 2019 at 6:47 am:
That’s not a matter of opinion. Whether someone thinks albedo affects the amount of solar energy being absorbed (as HEAT) by a planet or not, is irrelevant. It DOES (!!!!) affect the amount of solar energy being absorbed (as heat) by a planet. That’s what albedo does – it reflects a certain portion of the incoming flux of radiation from the Sun directly back out to space, and in so doing makes sure that this portion is never absorbed by the planet, which in turn means that the energy thus being reflected can never affect the system temperature of the planet in question.
This should not be a controversial point …!
Could people here PLEASE think this whole thing through and come back to what this issue is all about – Thermodynamics!
The TSI from the Sun is NOT – repeat: NOT (!!!!) – a thermodynamic transfer of energy to the Earth system. And so it can NOT be directly related to the TEMPERATURE of the Earth system. The temperature [T] of a thermodynamic system is integrally associated with the internal energy [U] of that system, and the system’s U (and thus its T) can be determined at the steady-state balance point between TWO kinds of energy transfer only: net HEAT [Q; Q_in minus Q_out] and net WORK [W; W_on minus W_by]. Leading us to the 1st Law of Thermodynamics:
ΔU = Q – W
The Earth system does no work on its surroundings (Sun/space), just as its surroundings do no work on it, which means its W is 0, and its U is fully maintained by its Q alone, the balance between its incoming HEAT flux [Q_in] and its outgoing HEAT flux [Q_out].
The only question that remains at this point is the following: What fluxes constitute the Q_in and the Q_out, respectively, of the Earth system?
Hint: TSI is not one of them …
No, the answer is very simple:
Earth’s Q_in is the global all-sky ASR flux at the ToA, the net SW, the incoming SW radiation from the Sun (the TSI) minus the outgoing SW radiation from the Earth system (reflected to space by its global albedo): [340-100=] 240 W/m^2.
“ASR” stands for “Absorbed Solar Radiation” and is the solar heat flux to the Earth system.
Earth’s Q_out is the global all-sky OLR flux at the ToA, the net LW, the incoming LW radiation from space (effectively zero) minus the outgoing LW radiation from the Earth system (emitted thermally to space): [0-240=] -240 W/m^2.
“OLR” stands for “Outgoing Long-wave Radiation” and is Earth’s heat flux to space.
Earth’s NET heat [Q_net or just Q], then, is ~ [240-240=] 0 W/m^2.
So, in the steady state, with a perfect heat balance at the global ToA, heat out equals heat in, and so the overall system U and T both stay unchanged. (U and T are free, however, to vary locally/regionally inside the system, even with no change in the overall balance.)
But this balance is between the ASR and the OLR, the HEAT fluxes of the Earth system, not between the TSI and some fabricated ‘flux’ (SW_refl + OLR; the SW_refl is not (!!) part of Earth’s heat loss to space, it rather takes away from (reduces) its heat GAIN from the Sun; basically equivalent to the way “the atmospheric back radiation” (DWLWIR) to the surface is not a separate positive thermodynamic transfer of energy, but rather an expression of the reduction (the “negative half”) of the surface radiative heat LOSS, which very much is a separate thermodynamic transfer of energy).
–Ben Wouters says:
February 17, 2019 at 8:41 am
gbaikie says: February 17, 2019 at 6:47 am
I think Albedo effects how much sunlight is absorbed.
And Moon is black as coal and the Moon absorbs very little sunlight. It not clear to me how one could make body absorb as little sunlight as moon does
Imo Albedo is just a number that indicates what percentage of incoming solar radiation is REFLECTED, and thus has no effect on the temperature of a planet.–
I would say, far less effect as compared to what a lot people seem to imagine.
[and since Venus clouds reflect/scatter sunlight, and IMO the clouds cause the Venus rocky surface to be very hot, “Albedo” can make a planet hotter.]
–The moon absorbs ~90% of incoming solar, Earth ~70%.
The difference between the two is the composition of the surface.–
The big difference is the ocean surface which covers 70% of the surface of Earth.
The average surface temperature of ocean is higher than average land surface.
Ocean: 17 C and land 10 C.
On Earth, the land surface when sun is near zenith can reach 70 C whereas ocean surface max temperature is about 35 C.
If surface of ocean is 30 C, the air temperature is about 30 C. Or ocean surface is surface air temperature. Land surface is quite different than surface air temperature- or roughly about a 20 C difference or more.
In a parked car, insulated box, or a greenhouse air temperature can reach about 70 C. And within solar pond water temperature can reach and maintain water temperature of 80 C. Or can maintain the same temperature during the night. An ocean has some similar aspects as a solar pond, but I would say ocean absorbs and warms the rest of the earth slightly more than a solar pond.
A solar thermal collector absorbs a lot of solar energy and solar pond is one of best solar thermal collector in terms percentage of heat it can absorb. In terms of usefulness of thermal energy collected there number problems with solar ponds, but the amount sunlight absorb is not one of the problems, unless the water becomes less transparent [that one problem, but not a problem which difficult to solve- and I will also note that for most part, our ocean do not have this problem, as it has most of surface being very transparent water.]
The other big difference of Moon and Earth, is Earth has atmosphere which also absorbs a lot of energy- per square meter more energy absorbed as land can absorb, though land absorbs sunlight and heats the air above it. And wet land would absorb more sunlight energy and transfer it to atmosphere as compared to dry land. And if Moon had wet land it would absorb more energy and whether it’s wet or dry makes little difference in Albedo.
–Lunar regolith warms up very fast, but only max.~ 50 cm deep.–
No. The top 1 mm of lunar surface warms up fast. At say 12 cm depth it warms up extremely
slowly. Dry Sand on Earth to depth 50 cm, warms up as fast or faster.
The Moon has days where sun is near zenith and amount warms up to depth of 12 cm is very slight.
–okulaer says:
February 17, 2019 at 7:38 pm
gbaikie says, February 17, 2019 at 6:47 am:
I think Albedo effects how much sunlight is absorbed.
That’s not a matter of opinion. Whether someone thinks albedo affects the amount of solar energy being absorbed (as HEAT) by a planet or not, is irrelevant. It DOES (!!!!) affect the amount of solar energy being absorbed (as heat) by a planet. That’s what albedo does – it reflects a certain portion of the incoming flux of radiation from the Sun directly back out to space, and in so doing makes sure that this portion is never absorbed by the planet, which in turn means that the energy thus being reflected can never affect the system temperature of the planet in question.
This should not be a controversial point …!–
I always try to say what is true. And it’s not always controversial, particularly to everyone.
But I could paint the Moon white and make it absorb more energy and the Moon would reflect a lot more sunlight.
I could cover the Moon will snow, and have absorb more sunlight. As said, would be hard to make anything that would absorb less energy from the Sun, as compared to the Moon. It is a true wonder of nature.
gc – So what can be generating such huge amounts of heat? (on Jupiter)
Same as Venus – atmospheric pressure.
J – Surface Pressure: >>1000 bars
https://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html
gbaikie – That’s what albedo does – it reflects a certain portion of the incoming flux of radiation from the Sun directly back out to space, and in so doing makes sure that this portion is never absorbed by the planet, which in turn means that the energy thus being reflected can never affect the system temperature of the planet in question.
This should not be a controversial point …!–
And yet we observe that Venus with an albedo of 0.75 has a surface temperature far in excess of Earth, even though its incoming solar radiation is only 17-18% greater (4th root of 1.911), and albedo theory expects 75% of that radiation to be bounced back into space.
Average temperature: 737 K (464 C)
https://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html
(see: solar irradiance)
But…Surface pressure: 92 bars (Earth = 1 bar)
“I end up feeling like Matt Dillahunty in the video below, trying his best to spoon-feed reality to an indoctrinated Christian nitwit”
I am not sure who is the nitwit.
I think God exist.
I think Christianity caused science to exist. Though Christianity is not science, though science was created by those with faith in certain principles.
That I think God exist, does not compel me to prove that God exist.
I don’t think a god needs my help, if anything a god could help me.
God is great and doesn’t need fans. Though some fans might need god.
And it seems possible that these fans might get some assistance from a god or
God. It seems there are some beneficial aspects connected to having faith in any
of the Great faiths of this world. And that seem like this something one could prove
as true. If there was not a god, then it seems unlikely to me that you can could able
prove this.
I am not generally impress with “the works” of atheism.
Atheism is not about the lack of faith in God.
Doubting the existence of God is part Christianity, or lacking faith an important aspect
of the faith. Or Atheism has not “invented” something and added much to dialogue.
Though when a person is declared Atheist, and seems fairly smart and can say something
vaguely interesting, Christians will tend to show up and listen to what they have to say- or
it seems to be important and interesting topic for Christians [to their credit].
I am not a christian, but it seems that for Christians in terms the need of proof,
Christ is that proof.
I like Jews and their faith, and I think their faith provides evidence that socialism doesn’t work-
something like, 3000 years ago. But that’s my opinion, in regards to important lesson.. I also like other faiths- but atheism doesn’t seem very interesting. And teaching atheism in schools doesn’t seem be adding much to education.
I tend to blame much of pseudo science on atheism. And atheism is pseudo science.
Some atheists might be interesting, but atheism is pretty weak stuff. Roughly it seems to be worshiping the god of luck. Or we very lucky, but no one seems to particularly happy about having such luck.
@oldbrew,
“gc – So what can be generating such huge amounts of heat? (on Jupiter)
Same as Venus – atmospheric pressure.”
You impress me because you are well read.
Yet somehow you just said that pressure generates heat. Please tell me that you mis-spoke. Jupiter, Saturn and Neptune all appear to have significant internal heat sources.
So how do you explain that Uranus with internal pressure greater than Neptune seems to lack an internal heat source?
We need to resolve this.
Uranian Atmosphere
Surface Pressure: >>1000 bars
Temperature at 1 bar: 76 K (-197 C)
Temperature at 0.1 bar: 53 K (-220 C)
Density at 1 bar: 0.42 kg/m3
Neptunian Atmosphere
Surface Pressure: >>1000 bars
Temperature at 1 bar: 72 K (-201 C)
Temperature at 0.1 bar: 55 K (-218 C)
Density at 1 bar: 0.45 kg/m3
Mass of Neptune: Mass (10^24 kg) 102.413
Mass of Earth: Mass (10^24 kg) 5.9724
Ratio Neptune/Earth: 17.15
Mass of Uranus (1024 kg) 86.813
Ratio Uranus/Earth: 14.54
https://nssdc.gsfc.nasa.gov/planetary/factsheet/index.html
If put 2 1/2 Earths into Uranus, then Uranus has same mass as Neptune.
“So how do you explain that Uranus with internal pressure greater than Neptune seems to lack an internal heat source?”
Where does it say Uranus has greater internal pressure than Neptune?
Pablo says: February 17, 2019 at 5:21 pm
The oceanic crust insulates Earths internal heat from the oceans. Without crust the oceans would be sitting on bare magma and probably boil away. So the crust does insulate but the little heat that passes through it warms the oceans.
Pablo says: February 17, 2019 at 5:02 pm
Obviously the atmosphere insulates the surface from space and thus reduces the energy loss to space.
At 290K (no atmosphere) the surface would radiate ~400 W/m^2 directly to space .
The atmosphere reduces this to ~240 W/m^2.
So the energy loss is not even halved by the atmosphere.
I do not think this is very good insulation.
A Nocturnal Inversion develops on clear nights when the surface can radiate easily towards space and cools down rapidly. The air near the surface is cooled by the cold surface.
Air higher up cools much slower.
Don’t see what the adiabatic lapse rates have to do with this since they are only relevant for the temperature change of rising/sinking air.
okulaer aka Kristian aka ???? says: February 17, 2019 at 7:16 pm
It’s apparently very frustrating to be wrong so often.
BW says:
“Obviously the atmosphere insulates the surface from space and thus reduces the energy loss to space.”
No coincidence then that average air temperature determines average soil temperature.
Beg to differ on the relevance of lapse rates to only apply to rising or sinking air, but will just point out that surface air can cool radiatively at night more rapidly than the daytime warmed ground beneath it.
That is to say that in calm night time conditions radiative water vapour enables faster heat loss from near surface air than via conduction from the cooling ground.
gc – Yet somehow you just said that pressure generates heat.
Maybe there’s a better way to describe the lapse rate.
oldbrew says: February 18, 2019 at 9:29 am
https://www.britannica.com/science/lapse-rate
Ben Wouters says, February 18, 2019 at 6:14 am:
That’s coming from a man who persists in showing his complete lack of understanding of the (thermodynamic) principles of regular heat transfer XD
He denies the reality of convective heat transfer, and he denies the fact that a warmer surface (yes, from being heated by the Sun ***AND*** insulated by the warm atmosphere on top of it) will make it harder for the energy from below to escape through that surface.
Pablo says: February 18, 2019 at 7:33 am
On planet Earth the surface warms the air just above it, so it is actually the other way around: surface temperature determines air temperature.
The ADIABATIC lapse rates only apply to rising or sinking air.
okulaer says: February 19, 2019 at 8:19 am
Quotes please.
Atmospheric convection removes heat from (usually) the surface and transports it upwards.
Since the proces is adiabatic it doesn’t change the temperature of the air it rises through.
I think I’m well aware of how atmospheric convection works.
(and NO, the Hadley cell etc. are NOT driven by convection)
Quotes please.
From https://tallbloke.wordpress.com/2014/03/03/ben-wouters-influence-of-geothermal-heat-on-past-and-present-climate/
” Obvious is that the surface layer is considerably warmer than the deep oceans, since it is warmed by the sun. This means that water heated at the bottom only can rise to a depth where its density is equal to the water it rises into. So the warm surface layer effectively shields the deep oceans thermally from the atmosphere.”
On average the atmosphere is COLDER than the surface, not warm.
BW says:
“On planet Earth the surface warms the air just above it, so it is actually the other way around: surface temperature determines air temperature.”
Air temperature slows down the cooling of the sun warmed surface. Consider soil surface at 15ºC and an air temperature of 15ºC, what would happen if that situation was maintained?
BW says:
“The ADIABATIC lapse rates only apply to rising or sinking air.”
I am referring to the frictional turbulent mixing within the boundary layer throughout daylight hours realigning the stable atmospheric norm of a moist lapse rate (an increase of PT with height) to that of the dry (constant PT with height.) At daybreak with no loss or gain of energy from the sun or otherwise surface air temperature is raised a few degrees simply by mixing that potentially warmer air from above with the cooler below thus cooling the air at the level from which the extra warmth came.( which actually creates an inversion at that height.)
BW says:
“Atmospheric convection removes heat from (usually) the surface and transports it upwards.
Since the proces is adiabatic it doesn’t change the temperature of the air it rises through.
What!?
Re – Pablo says: February 20, 2019 at 4:58 pm
Wiki: An adiabatic process occurs without transfer of heat or mass of substances between a thermodynamic system and its surroundings.
https://en.wikipedia.org/wiki/Adiabatic_process
oldbrew says:
Wiki: An adiabatic process occurs without transfer of heat or mass of substances between a thermodynamic system and its surroundings.
True.
The point being?
BW was saying heat removed from the surface by convection doesn’t change the temperature of the air it rises through!
Are you in agreement with that?
–BW was saying heat removed from the surface by convection doesn’t change the temperature of the air it rises through!
Are you in agreement with that?–
A warmer air mass rising, brings down colder upper air to replace it.
But the column of air mostly convects by transfers kinetic energy rather than the movement of air masses, though clouds tend to cause rising air masses [and descending air masses].
A rising air mass cools because it expands [becomes less dense in regard to volume]. And obviously descending air mass warms [as it become more dense].
I’ll go along with what it says here.
Adiabatic Heating
https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/adiabatic-heating
oldbrew…We understand adiabatic compression and expansion by now I hope, but you didn’t answer my question.
Do you agree that …
“heat removed from the surface by convection doesn’t change the temperature of the air it rises through!”
Convection and conduction are different things.
In gases heat will be mainly transported by convective heat transfer.
–oldbrew says:
February 21, 2019 at 8:48 am
Convection and conduction are different things.–
Ok but air conduction to objects is different than air conduction to air.
Or air conduction to objects is poor, and not poor with air conducting to air.
But some call air conduction to air, convection.
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter6/adiab_cool.html
Pablo says: February 20, 2019 at 4:21 pm
Not sure how air temperature can slow the cooling of the surface.
To maintain the soil at 15C takes energy, so what is your point?
Pablo says: February 20, 2019 at 4:58 pm
What do you not understand about simpel convection?
Pablo says: February 20, 2019 at 8:10 pm
Are you aware what adiabatic means?
gbaikie says: February 20, 2019 at 9:53 pm
Atmospheric convection IS the movement of air, driven by buoyancy.
clouds are (almost) always the RESULT of rising air masses. Sinking air causes clouds to dissipate.
Last try…
re. previous…Air temperature slows down the cooling of the sun warmed surface. Consider soil surface at 15ºC and an air temperature of 15ºC, what would happen if that situation was maintained?
BW says..”.Not sure how air temperature can slow the cooling of the surface.
To maintain the soil at 15C takes energy, so what is your point?”
Consider if air temperature remained at 15ºC (say with a sudden wind from the Sahara) above a dry surface of the same temperature at dusk …. what would happen to the soil temperature over night?
Pablo says: February 22, 2019 at 10:39 am
Last try to achieve what? So far you are not making much sense.
Air temperature has no insulating capabilities.
The troposphere mostly insulates the surface from space, but even on cloudy nights the surface radiates some energy directly to space. On clear nights considerable amounts of energy are lost this way.
Try https://cliffmass.blogspot.com/2011/12/surface-air-and-soil-temperatures.html
for some basics on soil, surface and air temperature.
Obviously the surface will cool down, the soil below it at a slower rate.
BW…
Last try to convince you that an air temperature of a steady 15ºC would indeed insulate a surface at a temperature of 15ºC or even warm a cooler surface. How do you think central heating works?
–Ben Wouters says:
February 22, 2019 at 10:12 am
gbaikie says: February 20, 2019 at 9:53 pm
But the column of air mostly convects by transfers kinetic energy rather than the movement of air masses
Atmospheric convection IS the movement of air, driven by buoyancy.–
That is one type of convection of air.
Air is molecules which is earth’s atmospheric molecules have average velocity of about 400 m/s [400 m/s equals about 900 mph]. Earth atmosphere is mostly nitrogen and oxygen and the density of type of gas causes a different velocity at same temperature of air- dense gas has lower average velocity, and a less dense gas has higher average velocity. The trillions of air molecules colliding every nanosecond produces the average molecule velocity.
In troposphere air density, the individual molecules don’t go anywhere relative to the trillion of other air molecules [there interacting with other other and going random velocities and random directions in distance traveled measured in nano meters, but mass of air molecule can have “weight” and can have buoyancy and can move as a mass of air relative to other masses of air. [or relative to the ground or whatever].
Or other way to say it: a speeding bullet or molecule doesn’t have buoyancy.
gbaikie says: February 22, 2019 at 5:24 pm
What you describe is the state of Hydrostatic Equilibrium against gravity the atmosphere is in.
Air pressure “pushing” the column above it up against gravity.
All those colliding molecules provide this pressure at every altitude.
Q. J. R. Meteorol. SOC. (2001), 127, pp. 2353-2366
Water’s two height scales: The moist adiabat and the radiative troposphere
By BRIAN E. MAPES*
NOMCIRES ClimateDiagnostics Center;USA
(Received 4 July 2000, revised 25 January 2001)
SUMMARY
The temperature structure of the tropical troposphere resembles a moist adiabat, with a lapse-rate transition toward dry adiabatic where water becomes scarce at an altitude 8 km (350 hPa). Infrared emission by water vapour cools a deeper layer, extending up to 14km (160hPa). Five consequences of these unequal heights heights are reviewed.
1. Upper-tropospheric relative humidity is often low, highly variable, and bimodal, due to the rapidity of drying by radiative subsidence.
2. Large-scale divergent circulations (e.g. equatorial wind) exhibit a two-celled vertical structure, with an elevated convergence layer near 8-10 km in the rising branch.
3. The dominant deep convective heating process changes from latent heating at low levels to eddy heat-flux convergence in the upper troposphere. This requires a substantial updraught-environment temperature difference, which leads to large entrainment near 8km, yielding stratiform anvil clouds which also contribute radiative heating.
4.The rising branches of deep 14km vertical circulations export more heat than they import as moisture, so that large-scale tropical dynamics can be characterized by a ‘gross moist stability’.
5. Divergent motions with a vertical wavelength -8 km, corresponding to Kelvin or gravity wave speeds of -15 m s-’, are excited by simple (e.g. uniform) heating profiles extending through the lapse-rate change near 8km.
KEYWORDS: Gross moist stability Radiative-convective equilibrium Tropical atmosphere Vertical structure
Click to access a28dd01bc3113e718b2ac90e1fae0ace487a.pdf
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